Are you referring to the S-video/Composite output that fits in the monitor-out slot?
I've tried it with the 6200 and it worked for the most part. I think there are a few flukes when using it with other systems, primarily dealing with reoslutions and colors.
All AV cards and TV/FM cards are compatible with every other Mac that has the same slots which is 580, 63x, 640, 52xx, 5300 (not PowerBook), 5400, 6400, 5500, and 6500.
There are two versions of the card. One has a long blue connector (looks like an internal IDE connector) and the other one has a shorter black connector (looks like a PC floppy connector). The connectors, I don't think were ever used.
The blue connector card is newer. The black connector card is older.
Actually, Mike, the connectors were used. The older ones (Rev. A/B, from memory), had the shorter connector for use with the Apple MPEG System (an LC PDS MPEG Decoder). The newer ones (Rev. C/D from memory) had the longer connector which was used with the Avid Cinema card that was an optional extra for the 6400, if i recall.