"All Sony machines needed a TBC to meet
FCC requirements, but I could feed a $79 VHS tape into our Vital
Industries Squeezezoom and get a picture that was stable enough to
broadcast.
"

I find that extremely hard to believe. I do believe it about the Sonys because of tape drag, but I find it hard to believe they let you broadcast right out of a VHS. You sure there might not have been another TBC downsteam ?

Some Sony pro equipment just incorporated the TBC, did someone turn it off or something ?