If you have a newer Camcorder, It may have what is called "Pass Through Mode"
or Analog Video Dubbing..
Some of the Camcorder makers made these options so that people with the older
video recorders could transfer their video from the older analog video recorders
to their computers or to the newer Mini DV without losing a lot of the quality of
the original tape.
In "Pass Through Mode", your newer camcorder acted as a analog to digital
converter, so that you can transfer your older video to a computer.
You play back your tape in your old camera through a AV cable plugged
into your new camcorder and it would convert and transfer the video through a Firewire cable to your computer.
In "Dubbing Mode" you could play back your old video camera into the newer
digital camcorder through a AV cable and the newer digital camcorder
would record everything to the mini dv tape in the digital camcorder, or
you could put a tape in your VCR and then play it into the digital camcorder
and transfer the recording that way.
Here is a web site with a list of camcorders that do some of these things.
DV Camcorders with pass-through
Now some of these camcorders are discontinued and you can still
buy one on Ebay really cheap and get your video transfered over to
something newer to work with.