I have noticed on the handheld cameras and on this VCR, which I use for digitization, that they are quite smart in the way that (even) if I fast forward the tape, the counter stops as soon as there is no video/data, which is really useful when setting up bash scripts for the recording. However, some tapes display video and audio when monitored - in my case with mpv on Linux - while the VCR's counter is still. The video and audio signals are perceivably degraded with a lot of noise and distortion.

Does this mean that VHS tapes lose magnetic charge over time? Does it mean that all ferromagnetic media lose charge over time?

I hope my ungrateful colleague (see this post) will still be happy for the little I was able to recover without professional equipment. 🥲