Don't hold your breath.
There currently are no drivers for OS X supporting the video-in or -out ports on the "perch" cards found in some Beige G3s, and I would not expect any, ever. Apple certainly won't write software for hardware that hasn't been made for almost 4 years; and they have been reluctant to release the kind of documentation that other parties would need to fill in the gap.
Furthermore, the drivers that are used under OS 8 or OS 9 won't work when running in the "Classic" environment under OS X, because they won't have direct access to the hardware.
So, if you want to continue using your video in and out ports, don't go with OS X.