"A patent pool is being assembled to go after Theora and other “open source” codecs now." That's kind of scary.
Now, just because you create something doesn't mean it doesn't infringe on someone's patent (read: it could infringe a patent). However, google presumably did some serious due-diligence before forking over their measly $133M, especially on the patent position. That doesn't make mean they're right, but it does mean that they think the patent position is pretty strong. Of course, they would have focused on VP8, the one they bought, not Theora's VP3 (and which might infringe due to subsequent open-source additions.)
Google might open source VP8 on May 19-20 http://www.reelseo.com/html5-vp8-google/