I see this a lot. It purports that Jason Garrett-Glaser has done an expert analysis of all of MPEG-LAs patents and has proclaimed specific infringement by VP8.
Of course that's complete bullshit. His analysis was superficially that there are similarities, and thus there may be infringement. Not one actual patent claim was shown to be infringed upon, much less even referenced to show that there was any understanding of it.
His analysis was as a codec guy. Not as a patent guy.
The devil are in the details.
It turns out (ha ha!) that when people vying for standards lay their patent traps, they tend to be extremely specific, ensuring that they don't get caught by prior art (there is plenty), but that they trap anyone who implements the standard. See Microsoft ActiveSync patents as a perfect example of this.
Does WebM infringe patents? Almost without question, as is the nature of the ridiculously generous patent system. Just as h264 is almost certainly infringing on patents of other parties that just haven't come forward to make their claims yet (and for which a h264 license is zero protection).
But one gets the sense that the author sees it as some sort of devastating argument.
Just as Gruber's post was framed. Google supports Flash, therefore they can't possibly be open, therefore Google is closed, therefore Google is evil...or something like that. Preaching to the choir and all that so I don't think much critical thought is necessary.