The big difference is MPEG-LA has gone through extensive public effort to document and find patents applicable to H264. On2 may have done the same, but they did so behind closed doors if they did. So far Google hasn't let us know either.
So oddly you have a royalty-based codec where work has been in the public. And a royalty-free based codec where everything has been done behind closed doors. Oh the irony. :-)
I think you can be sure that Google tripple-checked everything before exposing themselves to lawsuits and spending on On2 more than lifetime royalties to MPEG-LA (at current rate).
Another thing is that VP8 is very similar to H.264 without stepping on known H.264 patents. If any unexpected patent surfaces, both Google and MPEG-LA licensees will be screwed (but not MPEG-LA, as they're not giving protection nor guaranteeing that their license covers all required patents).
I think you can be sure that Google tripple-checked everything
They may have. If so, just show me the paperwork. MPEG-LA has given them a great paper trail to work from. The fact that I've seen nothing from Google gives me nothing to go on.
One thing I've learned in business is if one person gives you a docket full of easy to follow evidence and another says, "trust me" -- I tend to go with the hard evidence. In both cases the proof won't be complete, but I can sleep at night knowing that I made an informed choice.
But that's just me. At the end of the day, each org will have to make its own choice. I think a WebM + H264 world is perfectly fine. Let the better codec shine.
So oddly you have a royalty-based codec where work has been in the public. And a royalty-free based codec where everything has been done behind closed doors. Oh the irony. :-)