I've always been interested in video capture, and I finally got to play around with it recently on my PPC Macs. I bought a device on eBay called the InterView, made by XLR8. It is a USB 1.1 video capture device and it came in the box with software and drivers. It is designed with OS 8.6 in mind, so I tried it on my PDQ first. Installation went smoothly, I installed the included Strata VideoShop 4.5 first and then the drivers for the InterView.
I tested the device out by hooking up a model 1 Sega Genesis and playing some Sonic 2. Watching the game on the screen was fine with a hint of slowdown here and there (though I think that normally happens with this game now that I think about it), though I did have to turn Virtual Memory off to get better performance. Recording the footage caused the footage to appear as a slide show on screen and made playing more difficult. The footage looked okay when I played it back though, low framerate, but better than it was. I eventually discovered that there are a ton of different compression options in VideoShop with varying results of quality. I haven't tried them all out, but so far I like the Component option the best. Learned that the sound in port works on my PDQ, first time I ever used it.
I then decided to test for OS 9 compatibility by installing VideoShop and the drivers on my iBook G3. Due to the lack of a sound in port on the iBook, I used an RCA to USB converter to get sound in. Installation went smoothly and when watching the game on screen I noticed the performance was better. Recording turned the image on screen into a slideshow though. When played back however, the footage looked great once I found a good compression method. When I tried to close the the recording I was watching, OS 9 froze. I am unsure if this was a coincidence or if there is some incompatibility between VideoShop and OS 9 since this didn't happen to me on OS 8.
OS X drivers do exist for the InterView, but I don't know which version of OS X they need or if they work with my version of the InterView, so I haven't tried them out.