I figured out what it was doing. It is attempting to play the video on the list, failing to find a stream, and then going quickly to the next one on the list.

This is why it appears to be freaking out running down the list really fast when I select a particular channel.

If you pick a channel that does not have a working stream, then it goes on to the next one. In the case of the Discovery Channel (and now many others that I have found) it will keep trying the next link in the list until it finds one that works.