Tinic Uro has posted a lot of information on the new file extensions that will be used by Flash video, given the fact that H.264 encoded content will become more and more popular and important over the coming months.
The primary reason for the move away from .flv for H.264 encoded content appears to be compatibility: Adobe want to ensure that a file with a a certain extension is compatible with Flash. The primary extension for H.264 compatible video in Flash will be .f4v. Other file formats include .f4p for protected media, .f4a for audio files and .f4b for audio books. You may still use .flv for these files (the Flash Player will not look at the extension anyway) but I guess this is discouraged. If you run your own web server then I recommend you add the necessary MIME types now (they are listed on Tinic's site) or ask your hosting provider to do this. I remember many issues a few years back when .flv became popular as web servers did not know how to serve that format in a way that browsers could understand.
The primary reason for the move away from .flv for H.264 encoded content appears to be compatibility: Adobe want to ensure that a file with a a certain extension is compatible with Flash. The primary extension for H.264 compatible video in Flash will be .f4v. Other file formats include .f4p for protected media, .f4a for audio files and .f4b for audio books. You may still use .flv for these files (the Flash Player will not look at the extension anyway) but I guess this is discouraged. If you run your own web server then I recommend you add the necessary MIME types now (they are listed on Tinic's site) or ask your hosting provider to do this. I remember many issues a few years back when .flv became popular as web servers did not know how to serve that format in a way that browsers could understand.
More information can be found on Tinic's blog.


Just one question... Will FMS3 be able to stream these kind of files?
and what about books... how is that like?
thank you!
Books - no idea :-)
There is a better solution to force files to open in the correct player: meta files. WSX, ASX, RAM, QTL.
Adobe: leave MP4, M4V, MOV, 3GP for what they are. These are the official file types for these containers.
Adobe forces customers to copy and rename the same files just to get them to play in Flash. Confusing! More storage! Less flexible!
Here's a free tip to Adobe: don't be evil: introduce your own referrer file type. XML file (like ASX) with the FLX extension.
Oh yeah, and open up the transport protocol. Stick to standards. Don't rip-off RTSP but stick to it. Forget RTMP.