Support for the Video tag is generally poor among browsers. It's simply not as mature as Flash is.
I'm sure about that. As I already said, Flash has had a head start of essentially forever; surely it is between the most "mature" technologies in the current, everyday Web.
It's only a pity that for Flash "mature" only means "old", instead of "stable","reliable","safe", etc etc.
So, no surprise that HTML5 video is not as mature. As I said, it is not even finished, isn't it?
Judging by the benchmarks that have been carried out it would seem to be ideological.
Flash is by no means the most efficient thing in the world, but in real world scenarios it performs better than HTML5 video.
Can you please point to some "real world scenario" which would allow me to forget what I see everyday on my Mac?
Same thing for benchmarks, of course: do you have any link? Because part of my problems with the different browsers come from their behaviour with Flash content, so I would really like to see if things have gotten any better.
The really interesting question is: how would have Flash evolved if Apple/Jobs had not taken such an anti-Flash position? Would it still be as unusable on the Mac as it was?