As the experiment done and described here some time ago to capture Copy Free program from cable box to JVC DVHS deck directly through FireWire failed producing recording full of artifacts, I found that same program recorded onto Macbook looks perfect with no loss whatsoever.
Today the attempt was made to transfer this particular recorded program from Macbook to DVHS tape and result is the same (artifacts, pixelization) as it was recorded directly from cable box without Macbook acting as "middle" guy.
So it seems that the cable box outputs stream which is not fully compatible with DVHS deck making the direct recording impossible. On the contrary, the deck records perfectly any high definition FTA programs using HDTV antenna. It also records perfectly mpeg-2 videos prepared on computer as long as they comply with stream bitrate limits for dvhs recording.
It would be interesting to find out what exactly in captured from cable box stream makes recording to dvhs impossible. Unless someone already figured it out. Anyone?