At this web site from the California Institute of Technology (CALTECH) you will find a list of questions that have video answers available. To view a segment, simply select your connection speed after the format you wish to view the answer in. (Windows Media is more common for PC users, and QuickTime is more common for Macintosh users. However, players exist for all formats on all platforms.)
"How do stars live and die?"
"Why do we see spiral arms in some galaxies?"
"Can you feel a solar wind?"
"Why doesn't the moon fall down?"