These links might help:
How to insert Youtube Videos into PowerPoint Embed Web Videos in PowerPoint Presentations How to Embed Almost Anything in your Website
As explained in one of those links, it's potentially risky as it's dependent on a stable (& fast) internet connection, plus there's a possibility of missing video codecs on the host machine making a complete mess of everything.
This could get even more embarrassing if your college IT department blocks YouTube & Facebook.
Much safer to download the videos, convert them to either AVI or WMV format & then embed them directly into PowerPoint. The conversion bit is a failsafe as PPt can have trouble with the FLV & MP4 formats commonly found on Youtube & Facebook. This could be difficult for you as your school network admins probably won't let you download & install any 'unapproved' software. Any friends that use FireFox that can help you out?
However you do it, remember the three golden rules of presentations:
1 - Just because you
can do something (like clever animations or bells-'n'-whistles transitions) doesn't mean you
have to - less really is more.
2 - Give it a test run on a completely different computer on a completely different network before you present it. This will show up all sorts of potential pitfalls like font embedding, missing video codecs, dud hyperlinks etc.
3 - Copyright. Just because someone's posted it up on a website DOES NOT mean that the content has somehow magically become Royalty Free.
What's the topic for the presentation?
Pete.