Speaking of sync problems caused by pausing too many times, perhaps the wierdest video problem I have EVER encountered was a few years ago, when I wanted to record the SuperBowl from a HD network feed, however the computer I had my Twinhan card on didn't have any disk space left. I had a laptop on my LAN, which had about 40 GB, but I was calculating that the SB would take at least 60 GB or more. So what I did, was stream the signal over my LAN, and I set up VLC on my laptop not to play the HD stream, but to record it to file.
Since I didn't have enough disk space, what I would do, is when there was a commercial or other delay, I'd hit pause on VLC, then start it up again when play resumed. The biggest pause was during halftime.
Anyway, the next day, when I went back to see how my recording worked, it seemed to work very well, all the way up to halftime. When the 2nd half started, the recording went completely beserk. You'd see about 10 or 15 seconds of a play, then it would sort of jump back in time, and you'd see that 10-15 seconds again, and again, and again.... eventually it would break out of that sequence, and you'd see a bit of the game, then it would jump back in time again, and you'd again see a 10-15 second sequence repeated over and over and over again. It was the wierdest thing I have ever seen. Only good thing was that I got to see one TD pass about 50 times.
I put the thing into VideoReDo, and was able to at least pull out the non-damaged parts of the game, but VRD also had all sorts of trouble with the recording.
Anyway, I was convinved that what had happened was that my long pause at halftime had somehow completely messed up the timing of the recording, possibly related to the PCR... perhaps it isn't a long term clock, but a clock that recycles or something, I have no idea, but it sure resulted in the most interesting recording I've ever made.
BTW, when PCT was mentioned above, my mind was interpreting that as PCR, but now I'm not sure.