In a previous post by you say you have a GREX .There are instructions on their site for wiring a combo unit to record itself. The instructions may not be exact for your unit but should be similar enough.
Those that do this & want the best copy say a SVHS unit should be used for the input.
There is also an old method where a VHS video camera with a firewire out connected to a computer with a firewire in produces the best results. I beleive this creates a huge avi file. I don't know because I've never tried it.