[HELP] QTGMC appears to not be deinterlacing footage (or not doing so correctly)

[Perseverant]

I know a lot about ripping/transcoding/multiplexing, but when it gets down to the very technical aspects of different types of media and details around the best way to handle specific source types, that's where my knowledge falls off a bit, so the short answer is that QTGMC is what everyone appears to recommend as the best method for deinterlacing, which is what led me to your product.  Since the source was broadcast at NTSC 29.970 FPS I don't understand how 11.988 FPS would be preferable, but I will mess around with TIVTC.  ...but I don't know what I'm doing or why TIVTC might be more appropriate...

I'm sponge for knowledge, so anything and everything you're willing to share about these things would be much appreciated.  I would like to understand deinterlacing in particular more deeply.