I was looking for some simple youtube video to show how a photodiode works, so I could show it to my HL class giving me the chance for a 5 minute nap, when I came across Glesga physics. These have been put together by Valdo the professor of physics at Yoker university and I think they're brilliant. Maybe difficult to understand for non native speakers but there's lots of visual stuff too. Very funny.

Here's a sample: