Here is an application i had to develop in Actionscript 3, it lets you capture any content into a JPEG file (JPEG Encoding corelib class) with quality settings and size infos, you can choose between two modes, that lets you save the file on the server or your hard-disk.
Updated on the 09/20/06 : added FLV playback features
Updated on the 10/04/06 : added video navigation bar
Sources : Download
New AMFPHP Version available here