Here are a couple of my Exclude filter expressions:

TV-XVID
Code:
/(\.|\-|[ ])(DVDR|DVDRip|Pack|Complete|Custom|Hebsub|Bluray|Cam|1080p|720p|internal|Subs|TS)(\.|\-|[ ])/i

XVID UPDATED
Code:
/.*(\.|[ ])(DVDRip|BDRip).XVID\-(AMIABLE|Diamond|iMBT|ARROW|DASH|FLAiTE)$/i

And an example of a single snatch filter
Code:
/^Castle.2009.*.720p/i

or multiple snatches
Code:
/^(Castle.2009|Weeds.S07E*|The.Office.S08E*|Tosh.0.S03E*).*.720p/i