See what I did there?!
I thought I'd expand a bit on some thoughts I had while commenting on a Guardian story about the WebM controversy. I haven't seen anyone look at this angle, yet. (This is, of course, entirely my own personal opinion, and not that of my employer or any other organization I'm involved with. I am not a lawyer, a paralegal, or in any way involved in or an expert on any form of law or, for that matter, video encoding. I'm just an asshole with an opinion. This is not legal advice. If you want that, ask a lawyer.)
So, one of the concerns cited about WebM is its possible vulnerability to patents from entities other than Google. Yes, we have rock solid patent grants from Google covering the WebM spec, but it's possible other people have patents which cover functions you would need to implement in order to implement the WebM specification. So, the argument goes, you can't rely on the royalty-free-ness of WebM.
Well, that argument's true, as far as it goes. The trouble is it's also true of absolutely any software specification ever. There could always be some patent we don't know about. If that was going to stop us writing code, no-one would ever write code ever again to do anything. This of course is one of the major, major problems with software patents, but I don't want to go into that here. We've got the system we've got, and the practical upshot of it is that people still write code, and do the best analysis they can of the ridiculously over-large patent pool, and join things like the Open Innovation Network or the proprietary / secret equivalents, and cross their fingers.
To put it in practical terms - it's also possible that someone somewhere has a patent on a function you need to implement the H.264 spec. There's no legal requirement for them to have exercised it by now. The only guarantee we have that the MPEG-LA patent pool contains all the patents involved in H.264 functionality is the MPEG-LA's word for it. Hell, given the parlous state of the U.S. patent system, someone could go out tomorrow and retroactively patent some bit of the H.264 spec that no-one else got around to patenting yet, then sue the world. They'd eventually get slapped down in court, probably, but not before causing a huge amount of trouble and expense for everybody. It's perfectly true that some jackass waving a patent could cause trouble for WebM, but that's also true of just about every other piece of software.
Now, if we accept the premise that PWJs (Patent Waving Jackasses) are a general danger to civilized society, and think for a bit, it should become apparent that, relatively speaking, WebM is actually a pretty good bet. This is purely and simply because Google's now tied up its reputation and a degree of its interest in WebM. Google has gone out very publicly and said 'WebM is a royalty-free specification and we're going to back that up'. This is really very similar to MPEG-LA going out publicly and saying 'H.264 is a format covered by this exact set of patents and we're going to back that up'. Now, think about what happens if some PWJ comes forward claiming to have a patent that covers something in WebM.
What happens is, most likely, that Google makes the problem go away. This doesn't rely on Google's inherent altruism or anything ridiculous like that, but simply on Google behaving in its own best interests. Google has gone out and said people can implement WebM and not worry about patents; if people go and implement WebM and then get ambushed by a PWJ, and Google doesn't back them up, they're going to be really seriously narked at Google, and Google doesn't want that. Also, when Google says that it's backing WebM because having a royalty-free video format for the Web is in its own best interests it actually happens to be telling the truth. So both of those concerns will tend to cause Google to actually want to defend the royalty-free-ness of WebM.
So, if a PWJ does emerge, we can be reasonably sure that Google is going to go to bat for WebM. Google is a very good entity to have going to bat for WebM, for all the standard reasons in patent lawsuits: it's got deep pockets and good lawyers. Broadly what will happen is that Google will make the problem go away with money. Google's legal resources will help it make sure the amount of money involved is not too outrageous. First Google will assess the patent being waved. Possibly, if it's clearly trash, Google will call the PWJ's bluff and say 'sue us if you dare'; more likely is that the patent will have at least some degree of apparent merit. In this case Google's probably not going to actually go to law; instead it'll either try and buy the company represented by the PWJ, or pay the company to make a patent grant in the same style as Google's own. In most cases, Google is going to have easily the resources to do this. If anyone tries to screw too much money out of Google, they'll say 'okay, never mind, sue us; maybe you'll win, maybe you won't, but it's going to take years and cost you a damn fortune'. A company as big as Google can throw enough confusion into even the most apparently open-and-shut patent case to drag it on for years. Most owners of private companies, or shareholders of public ones, are going to take an immediate, definite payday over one that might be bigger but is uncertain and will definitely take a long time to arrive.
It's also worth considering that it's in Google's interests to actively seek out any submarine patents and deal with them as soon as possible, because it's all the easier to sell the legal uncertainty vs. potential return angle at this point than it would be after WebM gets serious traction. The potential value starts to look bigger at that point. So overall Google's probably going to have to spend less to deal with potential problem patents now than it will do in future, assuming WebM is successful.
Summary? Well, software patents are evil and PWJs are a menace to society. We knew that already. But when it comes to WebM, there is an extremely powerful entity in whose own interest it is to make sure PWJs are not a problem for WebM. So when it comes to worrying about patent threats, WebM is actually a pretty solid bet.
Of course, the ultimate PWJ for WebM is MPEG-LA. MPEG-LA would like to have us believe that it owns patents (or rather, it represents people who own patents) that cover WebM, and it damn well will not sell them to Google or make a public grant of them. It has rattled its saber as loudly as it possibly can to this effect, without publicly making specific claims about specific patents. (Some people will probably suggest this puts it in a very similar position SCO was in, regarding copyright claims). It is interesting, though, that it's been 'considering' this since April of last year, and has apparently done nothing.
There are conflicting opinions among those who actually know the icky details of video encoding techniques on whether WebM is likely to be subject to any of the patents in the H.264 pool. Dark Shikari - the author of x264, an extremely good F/OSS H.264 encoder (which is hence of course a patent infringer of comic proportions, and not officially distributed to the U.S.) - thinks it might be, while Carlo Daffara, who analyzed Shikari's analysis, suspects it isn't. I wouldn't want to venture a guess either way, but I would venture a small guess that it eventually winds up in court between MPEG-LA and Google, though I can also see that not happening, and MPEG-LA trying to pursue an exclusively FUD-based strategy without ever actually pulling the legal trigger. If that happens, it'll be a very interesting case, with potentially huge implications for all sorts of things.
A few people have suggested MPEG-LA will eventually make a very liberal patent grant on H.264 to make it effectively royalty-free for all web use, but I don't really see that happening. I don't see a way they can do that and keep any revenue stream on H.264, and MPEG-LA has absolutely no incentive to do anything without a patent-based royalty stream. It's an organization which exists entirely and exclusively for the purpose of generating patent-based revenue streams. All the individual holders of patents in the MPEG-LA pool could, I suppose, suddenly discover compelling business reasons to make such a grant, but I don't think it's especially likely (and it's even possible the terms of the MPEG-LA pooling agreement prevent them from doing so).