Horizontal Lines with GK Encoding

I rarely if ever get this problem with live action material, but when the source is a cartoon, I often get these horizontal lines whenever something moves quickly (generally mouth movement.) Anyway, I've been trying to tweak the AVS file, etc., but to no avail. Any advice to get rid of these lines? Thanks.

Don't double post.

It was not intentional. I posted here first and then realized that I should maybe ask the question on the Avisynth board as well. Anyway, it looks like I'll never get an answer to my question, so it's cool.

@HartleySan Hi! Sounds like your video requires deinterlacing...