Put a video onto video camera?

Sure!

Use a Firewire (also known as i.Link or IEEE1394) cable.

You may need to use software other than what is provided by Sony, but it needn't cost anything. Windows Movie Maker can save a project to tape over the Firewire.

You may also need a firewire card for your computer, if you don't already have one (or have a firewire input - some laptops do).

(Added comments after seeing Alias M's answer:)

That will ABSOLUTELY NOT work. There is no such thing as a cassette adapter that allows a miniDV tape to play in a VHS VCR. You may be confused about the adapter that allows playing a VHS-C tape in a VHS VCR. In the case of VHS-C, the recording is made the same way on the same width tape but in a smaller cartridge than VHS, and needs only physical adaptation to play in the larger tape slot. However, a miniDV is recorded digitally rather than analog, with a different set of tracks, on tape half as wide. There is absolutely no way it can be adapted to play in a VHS VCR, or anything other than either miniDV or DV or DVCAM VCRs. You are right about taping off a screen, though.)

qlink is correct... though since you did not specify a computer, it is a bit of a challenge...

With iMovie on a Mac, I just export the finished video back out to the camcorder - I presume MovieMaker has a similar capability... I do that all the time because it is the best way to archive highest quality video.

qlink is correct. But if you need further assistance try the Sony support site for your camcorder. They have tutorials and live assistance.Follow the link below........ Good luck!!