This is the modern format of choice because it's the most compatible. More users have Flash installed than any other media player, so more of them will be able to view your video than a video in any other format.
.fla - (flash) This is the development file, but this format doesn't run on the web. You use the Export command to convert your project into a .swf file, and that is what you actually upload to your server.
.flv - (flash video) This is the raw video file andis what you get after converting from .mp4 or some other format. This is what your Flash player will play. It stands for Flash Video.
.swf - (shockwave flash) This is the format of the Flash video player software. The extension stands for ShockWave Flash, an older name for Flash. Click here to learn how to make swf files and publish them on the web.
.f4v - (flash mp4 video) F4V is the standard MP4 files which has the ability to play back by Flash Player 9 or higher version. SWF files play f4v files.
.mov - (movie) QuickTime is a container format and can use any of several different codecs (coder-decoder ) for compressing the file (e.g., H.264, Sorenson, etc.). If you use QuickTime, save your files as self-contained (instead of "normal"), and note that the H.264 and Sorensen 3 encoders generally produces the smallest files with the best quality.
To embed the movie in your webpage you'd use HTML like this:
<embed src="filename.mov"AUTOPLAY=true CONTROLLER=true LOOP=false
PLUGINSPAGE="http://www.apple.com/quicktime" width="640" height="480">
.wmv - (windows media video) This is a Microsoft format and is not a good choice for websites because Mac users can't play them without installing additional software.
.mp4 - (mpeg layer-4) makes very small file sizes. Unfortunately Windows users can't see the video unless they download and install QuickTime.
.avi (audio video interleaved) - .avi is a container format, meaning that it's not really its own format, it contains video compressed with some other codec. That means that your computer might play some .avi files (where you have the proper codec installed) while failing to play others. Therefore, it is not a good choice for the web.