What are the differences between the various Mac video "compressor types"?
Most of these codecs you can read more into by doing Google Searches on them. I will try to summarize some of this for you:

Video codec is the traditional QuickTime codec used by Apple, going back a very long time. The quality is good, but it takes up a lot of space as it uses relatively little compression.

H.263 was developed for use in early web applications. Flash and RealVideo were two very popular web delivery mechanisms that utilized this system. It essentially is an update to the MPEG-2 encoding frameworks used on DVDs.

H.264 is an update to H.263 and offers even more space efficiency based on the quality. The overall concept of this codec (as well as many others) is to provide a full frame every x number of frames, and in the intermediate frames, to simply record the changes that have occurred from the previous frame. So if you have a frame of a person walking with a still background, only the data of that person's movements are recorded.

DV - PAL is a format optimized for outputting onto DV (digital video) tape, and PAL means it is designed for the European standard (vs. NTSC which is the broadcast standard in the United States).

Animation is a format, similar to H.263, but optimized for animation footage, where there will be many areas of the solid color. It also supports an alpha (or transparency) channel, which allows footage encoded in this method to be layered over other footage.