Laptop strange screeching sound

Specs:
Aspire V3-571G
Intel Core I7
Nvidia Geforce GT730 4GB dedicated VRAM
8GB DDR3
750 GB HDD
Windows 7 Ultimate.

I have the following issue with my laptop. This happened a couple of weeks a go as well but did not have time to look into it. It makes a screeching sound inside in the area of the radiator, where the heat is coming out at the left side. It only makes that sound when lean it forward and backward. In the recording I've uploaded now on youtube, you would think they're screws tumbling inside. However, I have shut down my laptop and it doesn't make the sound any more so it can't be something metalic moving inside. Plus... after starting the laptop again it stopped making the sound now. I wonder if the sound could be that the hard drive is about to die. However, I doubt the hard drive is in that area...
The laptop was overheating in august and had the radiator replaced.
Also, the motherboard and the hard drive were replaced a year ago, after I had other problems with it (posted them here at that time)
It's not overheating now.
Everything is working fine with it.
It's still in warranty.
Any thoughts on what could be the problem?
Here is the youtube upload with the laptop making that sound:
https://www.youtube.com/watch?v=jQcX8HIglSc

Thank you!
Kind Regards,
Patrick