I saw this analysis when it came out. He certainly may know what he's talking about but I think it's more likely that Google's due diligence would have caught these legal issues than an x264 developer. Not guaranteed, but likely.
As much as I suspected that WebM would be too hot to touch, the fact that the MPEG consortium hasn't done much more than posturing and clucking about the whole affair would seem to indicate that either WebM isn't covered by patents, or (more likely) that Google has some useful patents of their own that's keeping the hordes at bay.
It is a patent owned by a corporation that has chosen to license them in a royalty-free way, in the exact same way that MPEG-LA has chosen not to charge fees for end users of MPEG4. The main distinction would be source code access, but as stated by others, that is no guarantee of infringement of others' intellectual property rights. Stated another way: if you had the source code to the MPEG4 codec, would your objections remain?
You're probably right; I can't imagine that Google would have been careless enough to not have an army of lawyers look over everything before releasing it.
