a) if you have a rock solid videosource with great pausing you can grab some rather good pics. Notice rather is nicely put. You can ahve a live videocamera aimed att pictures and stuff and get some good pics.
b) you can grab b/w-images at a rate depending on your miggy, but it's not 24fps, not even close. Video on slowmotion can maybe produce a 24 fps b/w-anim. You can, however adjust the rate so it takes pictures every hour or so. Thats nice
c) Video in (composite) and s-video in. It's a box that goes to the parport, and almost blocks other ports. Its about 10*10*2,5 centimers so it's definitly in the way :-) I can recommend using a extension cable. The power is taken from the floppy port, so it takes up a floppyport aswell (if you dont use an external trafo). You can adjust some sort of brightness with a small srewdriver, and ofcourse from software (brightness, colour adn so on)
I haven't found any drivers for VHI for it, which is a shame, i guess. I have however found a nice rexx-script that uses it as a webcamera.
It's that enough information? :-)
If you can get hold of one cheap, and I mean CHEAP, its a rather fun toy. Since it grabs colourpics by taking r, g, b separetly I used it to create some 3d-images by first taking the red pic, moving the camera a bit, taking the green, moving, taking the blue and then composing them and view with those red/blue 3d-glasses. Pretty nice actually.
Come to think of it, I think I'm going to play a little with it right now. :-D