Recording Internet Video from Mac to VCR

Here's what I want to do ---
There is some streaming video that I wish to be able to show to a class. I cannot download it and burn it to a DVD, so I was hoping to hook up my computer to my TV, play the video and record it to a VHS cassette.

I have succeeded in using the TV as a monitor, with both video and sound, and I played the streaming video and hit the record button on the VCR.

However, when I tried to play it back, I just got several minutes of a screen that was blank except for the words "Unusable Signal." Obviously it had not recorded the video.

Does anyone know whether/how I can do what I am attempting?

Or is there a way to connect the computer directly to the VCR and record that way?

I realize this a backward process compared to what most people try to do with a Mac and a VCR. Please help!

(FYI, I am using a G$ PowerBook, running OSX 10.3.9, and Samsung VCR.)

Thanks.