Hi Barnes
I am not familiar with your camcorder but I found the following with my Sony (about 3 year old but high spec at the time) so perhaps the same is true:
1) When plugged in by USB I needed a driver on my PC (check Camcorder package for a CD or download from JVC site). Using USB, it works more like a webcam (with streaming quality) and the resolution captured from recording from tape is not of TV or DVD quality.
2) When plugged in by Firewire, there is full quality and editing capability is as you would expect, with synchronisation of stop and start during capture etc.
Therefore, if your camcorder is similar, you might want to use Firewire instead of USB.
I've a laptop so in my case a 4 pin to 4 pin cable was needed. If you've a desktop with a Firewire port, then 6 pin to 4 pin is probably needed.
Hope this helps.
Kind regards
Neil