He does the piece, the Flight of the Bumblebee, several times. At first it seems quite plausible, but everything at 300 or above seems faked to me. For one thing, guitar strings do have a limit at the speed at which they can 'speak' and the tempi above 300 seem to violate this. Also, if you look closely at his right hand, it does not seem to be a natural movement of the hand. Just an impression, of course. I'm not going to try to "debunk" this as, frankly, it is not worth the effort.
If music were a race instead of an art-form this might be interesting. But it's not...
Far better to spend your time and energy learning how to play like this:
That is David Russell playing the Prelude, Fugue and Allegro by J. S. Bach.