Short videos on the science topics you teach

I have always liked showing videos as part of my science classes, but I don't want to spend a whole period showing a video.  Plus, we know that the kids won't pay attention to a video that long anyway.  Check123 is a great site for finding short videos.  All areas are represented, but of course we all care about the science section. ;-)

The videos are all less than 4 minutes long.  You can do a search for what you are looking for and even narrow down the results based on the length of the video you are looking for.  For the most part these videos are hosted on YouTube, so if this is blocked in your school it won't work.  (On a side note, if it's blocked in your school you should really talk to the powers that be because it's a valuable teaching tool!)

What's one of your go to site for find videos for your classroom?