USB to PCI adapter?

[mikeselectricstuff]

That looks like a phono socket for standard composite video, though it could be at a nonstandard rate.
 Why do you think it's digital?

Sorry, I mean the "AUX I/O" port. By the way, that looks like a camera link...

It does look like Base Camera Link. That would have the serial pixel data, and it will also have the four Camera Control bits and the sideband UART. Buy a Matrox card and be done with it.

How can I make sure it's camera link or not before buying cards? These cards are not cheap, by the way, I won't have to ask if I can use a PCI card. Thank you anyway.

Find the exact model and find the data for it.
Failing that, look at the signals on the pins with a scope.

Some cameras do have both output, I just want to get the outside port to work, if a port it's not designed to be used and don't have a connector outside, it would be no help even if I take it apart.

But taking it apart may give you the answer.