A visual explaination of artifacts

The following are video clips shot with a variety of artifact problems. Click on the picture or the link to play the video. You may need to wait until the entire video loads before it will play correctly.

Here is a clip shot at Video CD resolution (1150kbps) - which isn't particularly great, but has minimal artifacts:
MPEG File - 920KB

Here is a clip shot at 500kbps, and poorly encoded. It is presented only as a demonstration of extreme digital artifacts:
MPEG File - 397KB

Here is a clip shot at the same low bitrate, with better encoding. It has artifacts typical of my digital cable:
MPEG File - 401KB

Note: audio was not included with these clips; it has nothing to do with artifacts and only makes the files larger.