After a brief chat with mattl in #jokosher I decided to hack together a little Grease Monkey script to find the FLV URL for a YouTube video (like extensions such as Fast Video Download do) then strip out the flash player and replace it with an <embed> tag, so a player like mozilla-mplayer can display the video instead.
No more audio syncing problems, no more jerky playback and most importantly no more non-free flash plugin . The only downside is that it has to buffer the entire file before it’ll play correctly.
Here’s a pretty screenshot of it playing a video about the One Laptop Per Child project.
And here’s the actual script if you want to give it a go:
When I get around to it I’ll see about adding support for more sites (google video, daily motion, etc.).