Is your JVC camcorder a digital camcorder?
What program were you using to access the movies on your camcorder? iMovie, I hope. You mentioned iPhoto but not iMovie. iPhoto will only work with still pictures.
The other thing is when you plug in your camcorder, you need to run iMovie. It won't start automatically.
Try plugging in your camcorder with your Firewire cable, run iMovie, and then tell us what happens.
If all else fails, you could erase iLife 05 by dragging iMovie, iPhoto, iDVD and Garageband and install the iLife that did work with your camcorder. I'm not sure if you'd have to erase the preference files. Possibly. They're in [your user name]/library/preferences folder.
Doug