What's this strange noise this guy's MacBook Pro makes?

For a few days now, my Macbook Pro has been making a sound I've never heard before in my life. I recommend you watch the last 20 seconds. It's not the hard drive. I sent it once to apple, they said they fixed it. But the noise came back.

To us it sounds like the fan straining from overuse. Perhaps it's even the hard drive, despite the owner saying it's not. Though, te sound is pretty similar to the noise one of my fans make in my desktop unit that's been clogged up with dust. Whatever it is, it seems like Apple should have fixed it the first go-round.

Thanks Diego!