Processing captured VHS tapes

[Selur]

From what I've read, I assume that Avisource is a codec that is superior to the built in libav HuffYUV decoder. Is that correct?

AviSource isn't a codec.
AviSource is a source filter which allows to use vfw decoders that are installed on a Windows system.
Whether those vfw decoders are better than their libav conterparts (assuming libav can decode the content too), totally depends on the vfw decoder.

Also, I assume I don't need to make any changes to the other default settings on the page Filtering->Vapoursynth->Misc->Source, as they are irrelevant to my files. Correct?

Correct. Assuming you got a 64bit vfw decoder in your system and Hybrid can use AviSource none of the other settings under "Filtering->Vapoursynth->Misc->Source" have any influence on the Vaporusynth script creation.

Cu Selur