[MeteorRain]

First things first, I would not recommend using QTGMC with such a long input in one shot. 493920 frames at 2.08 fps is 2.75 days, and anything could go wrong.

If I'm doing this, I'd split the video into multiple chunks (multiple AVS with Trim()s), run QTGMC without textsub, and encode to lossless avi (lagarith) or visually lossless 264 (--qp 6 for example), then join them together and put your subtitle on for the final encode. This not only gives you a much better error tolerance (only need to redo from save point), it also allows you to encode multiple chunks in parallel, if you have CPU resource to spare.

Also you definitely want to try AviSynth+.