I only know a program that can convert .swf to other popular video formats such as AVI, MP4 (iPod movie and PSP movie), MPEG, 3GP movie (3GPP/3GPP2) and and the process of both internal and external Flash video (FLV), etc-----Moyea SWF to video converter http://www.swfkits.com.
You can crop the picture and define the start/end time of SWF file before conversion; add edit watermark to the generated videos. The generated video would have no skipped frame, nor sound quality loss. The audio and video would be totally in synchronization.
As now as I know, Moyea SWF to video is a most suitable choice, because it offers advanced settings and options to meet their professional and state-of-the-art needs.