Dave Yeo has released (6/14/2010) a test build of
Seamonkey 2.1a2pre, which features support for the new "webm" video
format, and the same patches as Rich Walsh's Firefox 3.7a4pre build. Be
sure to get the "webm_fix" update from 6/21, which fixes crashes in the
mail/news client.
Source: OS/2 Warp News and Rumors