Many newspapers and magazines produce science podcasts. You can set up your RSS reader to automatically download podcasts so that you can listen to them later. Here are a few examples of science podcasts:
NY Times Science Times Podcast (weekly, Tuesdays)
Nature Podcast (weekly, Thursdays)
Many science journals and magazines also have video sections on their websites. For example:
New Scientist videos
Test Tube documents the “highs and lows of life as a scientist” in videos.
For a short video about each of the chemical elements, visit the Periodic Table of Videos.