I guess your right, for someone who is accustomed to just using one hand for the mouse and doesn't even touch the keyboard, it can be hard.
Like I said, when I play, I never touch the keyboard. I always play with the mouse and thats it. Thats why to me, I guess its no big feat.
One thing I did notice however, is that he abused the glitches and had saves pre-loaded (meaning he used saves for different games, at times loading a save that wasn't from that run).
He did abuse the system in order to gain those times. I think, if done right, a Fallout run could take much longer.