If you capture TV in AVI format, just play it back and do the stuff that I suggested above.
Should make a difference if you recorded in AVI or MPEG2.
Slim
EDIT:
Should not make a difference if you recorded in AVI or MPEG2.
Note: The process described entails digitizing the analog LINE OUT - LINE IN stream.
As Craig mentioned the capture is with Nero Vision and you select LINE IN as the source which is fed via a jumper from LINE OUT.
Both ends of the jumper are 3.5mm stereo plugs.
The sound card or embedded sound converts from digital to analog and Nero Vision converts the analog back to digital.