I have actually wondered how to do that before for a presentation in school, but didn't really matter because youtube is blocked at my school anyways.
That sucks. My school doesn't block youtube, but they just block keywords. That actually sucks though because sometime you are trying to go to an educational sight but they have it blocked.
Abit IP35-E Motherboard, 3Gig- corsair RAM
PNY 9800GTX+ 256MB DDR3 Video Card,
Core 2 Duo E4300 overclocked 2.2Ghz
SATA Western Digital 160Gig HD,
Windows 7, Dual 19" 1440x900 Monitors