MPEG-4 video +audio recording simultaneously.

Hello!
I am trying to record surgical procedures in the operating room. I have a pinnacle video transfer system given to me which connects via S-Video cable at the monitor in operating room (OR)to this video transfer device (VTD)VTD records the video in MPEG-4 format to the attached USB disk which is 8GB at present. Pinnacle's live help was exemplary! They said that VTD cannot store the file to computer directly. Being S-Video- it gas no audio!
what i want to do is- REcord the surgical procedure with video and audio commentary simultaneously, in MPEG-2/MPEG4 format, so that it is easy to learn at various points of the video. Secondly, when editing this 3 hour film in MPEG4 format (1.73GB),i would like a fast forwrad feature while editing so that a 3 hr video can be watched in 1/2 hour, unnecessary parts removed and kept again in MPEG2/4 format for later learning and teaching.
I am using vista (32 bit ), 2.53 core 2 duo, 250 GB HD
Pinnacle suggested that i record from monitor in OR to a camcorder, this will take care of video and attach a microphone to camcorder to record the live audio commentary. Any help will be graetly appreciated.