If it s only for the iPad, then yes, go for it.

The major problem with HTML5 video is that there is no agreement over which format to use. At the moment, some browsers support H.264, some support Ogg Theora, some support both, and of course, IE 8 and earlier (and older versions of other browsers) support neither. See Wikipedia for more details.

Edit in light of the question edit: Here s a quote from Steve Jobs recently posted "Thoughts on Flash":

...almost all this video is also available in a more modern format, H.264, and viewable on iPhones, iPods and iPads. YouTube, with an estimated 40% of the web’s video, shines in an app bundled on all Apple mobile devices, with the iPad offering perhaps the best YouTube discovery and viewing experience ever. Add to this video from Vimeo, Netflix, Facebook, ABC, CBS, CNN, MSNBC, Fox News, ESPN, NPR, Time, The New York Times, The Wall Street Journal, Sports Illustrated, People, National Geographic, and many, many others. iPhone, iPod and iPad users aren’t missing much video.

Given the list of video providers using HTML5 video (because that s how this H.264 video is delivered), I think you ll be fine.

Apple has a list of high profile sites that "iPad ready". Most of these sites use HTML5 video (at least when the iPad is detected). One other thing to keep in mind is that navigation can be different on a mutli-touch device compared with a mouse.

Yes, with caveats:

1. You’ll want a Flash player to use as a fallback for non-HTML5 browsers (i.e. Internet Explorer 8 and earlier)

2. You’ll need to encode the videos in WebM for Firefox/Chrome/Opera/Android, and H.264 for Safari/IE/iOS/old Android. (And possibly Ogg Theora if Firefox 3.5/3.6 and Opera 10.5 are important to you). Your Flash video player should be able to play the H.264 file, no need to separately re-encode there.

   I suppose this might be an issue for high traffic sites if they use caching for the video files? Because you’d need twice the cache space for your video files? But I’d guess for a high traffic site you’d have a dedicated media server for video, and having two versions of each file wouldn’t make any difference.

You’ll want to read the Dive into HTML5 section on video:

• Dive into HTML5: video

And you might want to look into using or customising one of these HTML5 video players:

• Video for Everybody
• Video JS