Unlike what happened with Doctor Who’s early years, Blue Peter apparently took great lengths to preserve their broadcast history. One reason several clips from lost Who episodes survived is they were used on Blue Peter.
U-Matic began life as a home video format that was too expensive for most people in the early '70’s. An early Sony U-matic home deck appears as a rich man’s toy in a Columbo episode as a plot device. It was still cheaper than most broadcast gear, and Sony refocused it’s efforts. It was firmly the format for colleges, small tv stations and other institutions by the 1980’s. Betacam was way too expensive for the college I went to. We received programming as an affiliate of National College Television on U-Matic tapes until direct satellite delivery took over in the 90’s.
I take great exception to your characterization of Betamax having used it many times over the years. U-matic was never more to me than a major pain in the ass back in college. The decks broke down so often you could set your watch by them.
Betamax was more or less the equivalent of VHS, 250 lines vs. 240 lines for VHS, and both Betamax and VHS recorded a lowly composite signal. U-matic was 280 lines (330 for the SP version) and recorded a Y/C signal (S-video), and Betacam was 300 lines (360 for the SP version) and recorded a YRyBy component signal, which is better than Y/C. When I said Betamax was junk in comparison, I was referring to picture quality, not to the quality/reliability of the hardware.
There were a few Columbo episodes featuring VCRs. Are you referring to the one where the guy has a home surveillance setup, complete with a room that looks like a TV broadcast studio? And Columbo solves the crime by magically zooming in on a speck-sized part of the video (a letter or an invitation or something) and it becomes crystal clear and readable?
What do you think that Mark Hamill video was recorded on? If not U-matic (and it does seem to be higher quality than U-matic, as far as I know, that only leaves Quad, and possibly 1" Type B or C, though that’s cutting it close for the time frame (some sources say Type B/C came out in '76 and others say '78). I’d be surprised if it was on Quad and they saved all those recordings, considering Quad reels are big (12 inches in diameter and a little over 2 inches thick, with storage boxes for them being 15 inches square and 4 inches thick), and with each one only holding an hour of video, it wouldn’t take long before you’d need an awful lot of storage space, and money too, at $300 each. If that’s what happened, then that’s impressive.