How do I write a filter that describes what I DO NOT want to download?

Example: I download a particular set of files by writing a basic filter like:

^Butterflys
^Moths

which downloads anything on the feed that begins with the word "Butterflys" or "Moths". However, I do NOT want to download files that are marked 720P. How do I say ALL Butterflys or Moths EXCEPT those with 720P?

In fact, I download several things (not just Butterflys and Moths) and have several filters to suit. I don't want 720P for ANY of them. So I'm looking for a way to simply block all 720P with a single filter, rather than have to go and (somehow) change a dozen or more filters to individually block the 720P versions.

foo(?!.*bar)

This will download all torrents with foo in them except when they are followed by bar. It's called negative lookahead.