Horrible electrical sound. Thoughts?

[Milsy]

Hi guys,

Check out the link to the video.

Horrible Noise

At around the 53 second mark you will hear an awful noise. It is much worse in real life

It is hit and miss on when it decides to happen, however generally it is when it is warmer, 30'c + (86'f +) and after I have driven the car for approximately an hour.

My thoughts are it has something to do with the alternator, as it starts fairly quietly and then builds up. It is a similar noise to an older car that needs a suppressor put on its alternator.

Your help would be appreciated. It is a hard one to get an auto elec to look at as it is hit and miss.

Cheers.

Brett