Short answer, just try to play the .mov file in Flash. Long answer: Flash 9 Beta 3 added limited support for the MP4 file format (or "container") and the H.264

Short answer, just try to play the .mov file in Flash. Long answer: Flash 9 Beta 3 added limited support for the MP4 file format (or "container") and the H.264 video encoding. The FLV container format does not and will never be able to contain H.264 data. MP4 is an ISO standard -- before that it was known as "QuickTime" aka ".mov". Yay! But MP4/.mov/QuickTime has very little to do with the actual video and audio encoding it contains. Your .mov file, which is an MP4-compliant container, may have video data in lots of different encoding formats, tracks, cover art, meta data, etc etc. Boo! Flash 9b3 supports only MP4 files with a single video/audio trak, and only moov atoms containing H.264 data. The file extension does not matter; it inspects the magic bits inside the file. There is not at the moment a cheap open-source way to stream these files. MP4 is an odd format: all frame metadata, usually about 2% of the total file size, is in the front of the file and MUST be fully downloaded & decoded before a video will start playing. Adobe is very aware of this and will gladly sell you expensive server software to stream H.264 video. :(