try adcritic.com or something? i dont know if you can download off of that though...
try googling some program that will let you rip youtube files or whatever onto your harddrive in a playable format
OR if youre going to be running the presentation off of your teacher's computer in class, just email yourself the links to the youtube page and pull it up on their computer...i do that sometimes when i have presentations and it works fine, professors dont usually mind.
"The best way I can describe it is it felt like somebody bungee jumped off my right nut."
-Ken Griffey Jr. on what it feels like to break your groin.
A couple sites to live by: