Spaced Ranger said:
I believe it!

I don’t.

AviSynth can decode MOVs with QTReader or QTSource. Try those. It’s been a while since I’ve used either. (I avoid MOVs like the plague.)

Also had v.2.6.0 installed once to try something from OT (with a few recommended plug-ins), but it wouldn’t work the script as it should’ve.

That’s rather vague, so I’m not sure what to suggest. While bugs are always possible, AviSynth is heavily used by some very knowledgeable people, so bugs tend to come to light. The frame-shifting problem that you’ve described sounds like it could be a decoding issue, and I’d sooner attribute it to that than to something fundamentally wrong with AviSynth’s ability to serve frames accurately. If you’re serious about investigating the problem, consider posting a thread over at Doom9 about it.

I guess the next thing to check into would be memory integrity (shudder).

Yes. That might be a good idea.