Gruber suggests that HTML 5 video is "effectively unusable" for the following two reasons:
- It doesn't allow poster images.
- Both audio and video always auto-buffer instead of waiting for a click.
There is the ever-present IE issue -- no version of Internet Explorer as of this writing supports
<audio> -- but this isn't at all an issue for Gruber.
Which seems, y'know, usable to me.