flash can do all sorts of things. i can remember when it was mainly for animations. playing video is just one of the many things flash can do.
there _may_ have been a need for something to replace mime and plugins, and for whatever reason macromedia's shockwave flash (swf) emerged as an interim solution. but adobe just abused its position. they are not an honest company when it comes to web users. they cannot be trusted.
html5 solves the problem(?) that flash was being used for, namely, playing media files through the browser. but we will have open source and we don't have to deal with a shady company like adobe.
html5 is not a flash replacement. you don't "transition" from flash to html5. html5 just keeps adobe and their sneaky tactics away from web video. and that's good for web users.
still, the fact remains, plugins (open source code not part of mozilla or another other browser, e.g., vlc or ffmpeg) are better media players than browsers. so i'm left to wonder if all this was really necessary.
stream this, stream that, but youtube is still using progressive download. so go figure.
last i checked mime still works. yet it was pretty much abandoned by the browser teams.
i'll bet there is really no good reason either.
just as there was no good reason we should be letting adobe control web video. adios adobe.