The question has been asked in a few posts "What file types are supported for conversion to Flash in Acrobat 9 Pro Extended". I will attempt to answer that (it is not totally straight forward or easy to explain)...
Acrobat 9 Pro Extended can embed or convert the following file types to Flash and embed:
3GPP (3GP, 3G2)
ASF
ASX
AVI
F4V
FLV
M1V
M4V
MOV
MP3
MP4
MPEG
MPG
QT
SWF
WMV
Keep in mind that not all files of the file types above will be compatible, the file extension denotes the "container type" for the audio/video but the type of audio and/or video inside any of these containers can still be an encoding type that is not supported (unfortunately video encoding is not straight forward). It is always good to make sure you can play back the file on your computer in Windows Media Player, Quicktime etc if you have any problems to make sure it plays fine outside of Acrobat.
Additionally Flash (FLV and SWF) can be embedded (listed above) if the video inside any of the container types above is "H.264 encoded" the file can be embedded and played back in Acrobat without converting to Flash (again there are cases where the audio or video track has different encoding that Acrobat does not understand and you may get white video playback or no audio playback, in this case try to covert rather than embedding the H.264, there is a check box you remove the check mark from "Maintain original H.264 encoding".
Also, you still have the ability to press the "Create Legacy Multimedia content" link from the "Insert Flash" or "Insert Video" dialogs which gives you the multimedia functionality from Acrobat 8 which requires the viewer to have the required media player installed for the video/flash to play back.
Now, Acrobat Pro is a little different If you are using Acrobat 9 Pro then there is no "transcoding" of video (it will not be converted to Flash) but any of the file types listed above can be embedded if the video encoding is H.264 and the audio is AAC. FLV and SWF can also be embedded with Acrobat 9 Pro. The "Create Legacy Multimedia content" is also available in Acrobat 9 Pro for any video files that are not H.264, selecting the files will direct you to the "Legacy Movie Tool" dialog (called "Add Move".
I hope that was not too confusing and gives some guidance... I will check back for questions.
Does that mean that Adobe Reader 9 will play embedded content created in Adobe Pro Extended 9 without requiring codecs, etc.? Or would the end user still have to have some sort of FLV/H.264 codec installed to view embedded video?