I wasn't kidding when I said that dev team in Japan never sleeps. Today, we released version 5.1.3.
This includes the latest Gecko engine (same as Firefox 3.5.1), which overcomes vulnerability issues. And yes, this also supports HTML 5 including native support for Ogg Theora encoded video and Vorbis encoded audio.In addition, we have fixed some bugs related to Windows Vista/XP and crash issues specific to Gecko.
Check it out and let us know your thought as always.