What exactly is ' Frame rate throtteling'?

I've been searching but I can't seem to find any sort of deffinition

I think it's a term used to describe the limiting of the frame rate to about 10-20 or to something more suitable.

But I can't seem to find any information to either confirm this or correct it.

Yes that's indeed what it is.

A number of games do this, for example the cut scenes in Half Life 2 are limited to 60 fps no matter what your hardware.

Thank you :)