Are you using Avisynth MT i guess :P
Be careful with FF3dfilter dont abuse it or the image will be full of jaggies. Second QTMC convert it to 59.976 fps , are you using SelectEven / SelectOdd to put it to 29.976 progressive? This video is pure interlaced so it will never be very smooth like the original source if you deinterlace it.
Is better if you use
This come at the end of the script to convert it again to 29.976 interlaced.
Always work in Avi without compression i recommend you Lagarith.
I'm using Avisynth MT, yes, though it doesn't seem to like having both QTGMC and SSSharp in the same script and keeps crashing. For now, I'm not using any of the MT stuff.
Using the combination of QTGMC, FFT3DFilter, and SSSharp has resulted in zero jaggies as far as I can tell, which is a relief. And yes, I am using SelectEven to revert back to 29.97fps. Reinterlacing at the end is probably the best way to go unless the filters don't require progressive video.
What I'll probably end up doing is splitting my master script into two separate ones, outputting the first half to a lossless codec (I've always used HuffYUV), then running that through the second half and outputting once more. Then I can run that into Premiere for the color correction.
I haven't had a chance to work on this since I posted the screens, but hopefully I'll have some time in the next week or two.