You didn't mention what type of MIDI interface you're using. If it's just the joystick port on a sound card and a "special" cable, that won't cut it. You'll need a more involved MIDI interface that has SMPTE capabilities. You will then feed the SMPTE code from the videotape into the SMPTE connector on the MIDI interface while playing back the VCR, watching the video, and playing the parts you want to record. When you're ready to mix down, you still need to sync to the SMPTE code off the Video tape while dubbing your finished audio to the VCR. Oh, I forgot to mention you'd need a VCR that allows audio dubbing and multiple audio tracks. Or, you could get a Video capture card and record the video AND SMPTE into your computer simultaneously, with a program such as Vegas Video - This would take either an analog or firewire capture card, or possible one of the fancier AGP cards such as the Matrox, that come with capture capabilities, etc - 'course, you'd STILL need the SMPTE capable MIDI interface...
Just in case you thought I knew what I was talking about, I don't - at least, not yet. I bought 4-5 books on the subject because I'm in the middle of a MAJOR upgrade to my studio (stereo to 5.1, audio for video, digital mixer + DAW + multitrack analog + analog mixer, 4 floated rooms with correct acoustics, separate computers for DAW and softsynths, etc) Anyway, what you want to do is not a simple task, and as near as I can tell, nobody who makes the stuff you need will tell you the truth about its REAL capabilities unless you have their left nut contained in a pair of Vice Grips and are tightening the little knurled knob with an evil grin on your face - sorta like the guys who sell digital audio stuff, huh?
For capture cards, check out
http://www.dazzle.com/main.html
http://www.pinnaclesys.com/start_new.asp
http://www.canopuscorp.com/
Watch all of these guys and dig into their FAQ's - some cards won't support win2k, some will but not XP, there are all kinds of "yeah but's" . You can't learn too much BEFORE you buy. I've got a long way to go on this before I buy also -
If you're short on cash, you might be better off finding a junior college with a good media center and taking a course, just so you can use their gear for your friend's project. The knowledge you pick up wouldn't hurt either... Steve