Just something to throw out there it would have been 10 times easy to just use a TV tuner on your Pc and just link the Vcr through that plus you have a connection to record from the tv and send it straight to the VCR or DVD recording device
Reason saying this my dad has a set up with multi TV and monitors with a VCR doing the same thing you're trying to accomplish
it would eliminate the headache right away ,just something to throw out there even though you figured it out
Also you could have use Windows Media Center as well Nero to me is too expensive to keep buying full copies