VideoJS has done a pretty good job at promoting HTML5 video and giving a viable alternative for Flash.

Flowplayer is not just HTML5 video but common API for video - no matter what the backend is: the VIDEO tag or Flash (for older browsers).

This universal API is for both CSS and JavaScript. Same CSS rules or JavaScript methods apply for both backends. Think of implementing plugins or skins that work on all browsers and devices.

That's not all. A lot of features that were only there for Flash are now available for HTML5: cuepoints, playlists, random seeking, fullscreen, keyboard shortucts.. to name a few. For a full list of features please have a look at:

http://flowplayer.org/why/

Demos: http://flowplayer.org/demos/

Make sure you try with various browsers. Note: iPad support is unbeatable.

Anecdotal, I know, but I found VideoJS to be a bit of a mess. From a code point of view, the player instance would not destroy correctly resulting in a memory leak for single-page web apps and IMHO the CSS was a pain to work with.

VideoJs is free (ass free speech), Flowplayer is not : it's a badgeware.

What about http://mediaelementjs.com/ ?