It was pretty clear from context that you weren't deliberately trying to offend, so I don't think anyone's going to be too upset. We've got people from all over the place here on this forum, and it's inevitable that honest mistakes will be made. I still remember being bewildered when the Brits I knew in Japan started laughing uncontrollably when I told them there was a store called "Fanny's Fabrics" here in Vancouver. Little did I know at the time that "fanny" has somewhat different connotations in Britain than it does in North America...

Anyhoo.

The question was about AviSynth: Depending on what input your MPEG-2 encoder needs, YUY2, YV12 or RGB might be needed. The encoded MPEG-2 DVD stream will be YV12, which is 4:2:0, and which is why many people who are starting with DVD as a source like to use YV12. Anything more is sort of overkill if all you're going to do is re-encode. YUY2 is, I think, 4:2:2, so more colour information is retained during processing. RGB is effectively 4:4:4 (although it's not planar), and therefore really good for processing, but not good for space and processing speed.

If I was starting with LD-sourced stuff capped to HuffYUV as either YUY2 or RGB, then I wouldn't want to go to YV12 until the encoding stage. If it was capped as DV (which is 4:2:0 for NTSC -- same as DVD), then I wouldn't worry too much about conversion to YV12 before encoding.

[My disclaimer: I just dredged this up from memory; I didn't do any recent research. One word: Google. Another couple of words: Doom9.org]