Yes. It’s data sent during “unused” parts of the video scan. It’s collected up, and put into memory, where it’s displayed in the same way that a video card works in a computer. It couldn’t happen until digital electronics made it viable in a small package.
It sounds like they re having problems sync’ing to the digital signal. But I can use the closed caption on old videotapes (well I have one where it’s delayed, and incomplete), so I’m not sure this would be a consistent problem. But maybe it’s because these were home recordings, so something is marginal.
It also sounds like they re using a sledgehammer for this, digitizing it all, then decoding in the computer. It would take a bit of wiring, making a sync decoder to get the actual portion of the scan with the data might be easiest, then they’d just have to decode the data in that portion of the scan.
