the html4 (90s tech) video standard was flv (swf).  the html5 standard (to replace flash security probs) is h264. 25 sec per frame is fast (no shadows, no IDL, low samples, hi-shade-rate, lo IC).  user joster here swears by preview-rendered movies.  he's posted sevl on u-tube. 3d snobs don't like preview renders, but mass audience doesn't care.