There ARE some good things on youtube.com, and occasionally these are useful in instruction. With the unrestricted proxy, it is possible to watch youtube and other items in the classroom.

The problem remaining is that planning on showing a streaming video from the internet to a class in real time is playing with fire. Slow connections, slow computers, unexpected outages, etc. can leave you with a damaged presentation with pauses and freezes. It could even result in total failure - no video at all.

The solution is to download the video you want to use to your computer outside of class time, then show it from your hard drive or flash drive.

Generally it is best to download in the "MP4" format. This should work on any of the computers we have at school.
It is also the standard for DVDs, Blue-Ray Disks, and all HD TV, both cable and over-the-air.

The HD option may not run properly on the older iBooks (2003 vintage), and for those it would be best to stick to the highest non-HD format of MP4.

I have tried the below on Mac and Windows, and it works well on both. It uses a JavaScript "bookmarklet". It uses only the software you already have plus the bookmarklet.

Instructions for doing this are at: deturl.com/bookmarklet-to-directly-download-videos-from-youtube.asp

Remember, on a Mac without a multi-button mouse you "right-click" by clicking with the Control key held down.

This page wouldn't be complete without my very favorite YouTube video:

• HDTV 1080 NASA Space Shuttle Atlantis
  Play this one full screen with the volume at 11. It always cheers me up.