Channels...??

I just fired up Media center for the first time this afternoon. After running through the configuration settings, it brought be to a nice list of available videos, which I started to peruse... After, I closed media center, and then later, when I re-opened, I cannot find any of the videos it had in there before. There were some good videos semi current on the Presidential election, etc.

Any advice.. Is that a one time deal? or is there a way to get back to those videos..?