I used to listen to TotalBiscuit back when I played WoW on his podcast "Blue Plz!". Truly [massive reverb]EPIC[/massive reverb].
Didn't know he'd moved to YouTube for LPs... Gonna have to check him out.
My personal favorite is Geop (or GeopLP, on YouTube). I came across him while perusing the Let's Play Archive and decided to watch the last couple missions of AC1, since I pretty much tossed my controller when I ran into the point that they changed the rules from "Be sneaky and fast; kill your target and go" to "Screw it, here's a small to fight; have at it."
I expected to have to skim the slider from cutscene to cutscene and skip over the travel and exploration... instead, I got to listen to a history lesson on the geopolitical climate of the region, punctuated by bios of the major historical players and the occasional "whoops, depth perception", whenever 'Al' decided to leap from a rooftop to the cobbled ground below. I actually watched the last missions, then went back to Episode 1, and started from the beginning.
He recently started a Let's Play of AC2, and I've not been disappointed.
Honestly, with Geop's LPs, I've come to love the Assassin's Creed franchise even more for their attention to historical detail. While they do get a few things mixed up, on the by and large they've done very well in their creation of their "alternate past" for the games.