Lots of resources on the Internet Archive that everyone forgets about!

Working with video Pictures, icons & fonts Sounds & videos
CamStudio - Sourceforge
A free version of Camtasia. Record what happens on your screen and turn it into video.
If you need sounds for video for your classroom, these resources will help.

This is what gamers use to make screen videos. If you just need a short clip or a very high res clip, it will do it.

I LOVE this site. I use it to rip YouTube videos so I can use them in class. Easy to use, just copy the URL and right click, save as the file you want.

This site allows many different file conversions, video conversions, YouTube ripping, etc. It does a lot of those odd tasks you need with files.

Tracker is really neat software that allows you to take any video and do the math with it. Excellent for using in class.
25 Sites for educational videos!