Cam: Filmed with a digital camera in a theater. The sound is captured via the on-camera microphone. Lowest quality. 
  
Telesync (abbr. TS): Video is captured via the same method as a cam release, but the sound source is different. Usually, the sound is captured directly from the receiver in the theater or a recording device placed next to a speaker. The sound and video are then merged and synchronized. 
  
Screener (abbr. SCRN): Source video and audio come from promotional VHS tape released to critics, owners of theaters, and owners of video stores. Usually features a message scrolling along the bottom explaining that unauthorized copying or distribution is illegal. Screeners can also be releases that were digitized directly from the movie reel, although this type is rare. With these specifically, you'll see the typical 'fuzzies' and 'holes' that you'd see on a movie screen in a theater. 
  
Workprint (abbr. WP): These are copies of the movie still in progress. These may differ in content from the final release of the film, as they are still being modified. Workprints are fairly nice quality, although rare to find. 
  
DVD Rip: Video and audio stored on a DVD disc are decoded, then written to a file. DVD rips usually feature the best quality, some even approaching actual DVD quality video and sound. 
  
DivX: A DivX media file features MPEG-4 compression video with MPEG-3 compression audio. Typical MPEG media files feature MPEG-2 video and MPEG-1 audio. DivX allows for smaller file sizes with much better quality than any other mainstream codec. 
  
Codec: Compression/DECompression. Codecs are drivers that allow your computer to play various media types.