The ever eloquent, informative and incredibly talented Stuart Brown, aka Ahoy, has released his visual treatise on the Quake series. This is the third part of his RetroAhoy series on id's "unholy trinity" of Wolfenstein, Doom and Quake, and it details the genesis and evolution of the late 90s shooter phenomenon. It doesn't go into nearly as much detail on my personal favorite of the series, Quake 2, but if you ever wanted to know everything about the origin, development and mechanics of the original Quake, and its long-reaching influence on gaming, this video is pretty much the last word.
At over an hour long it's essentially a mini-documentary, but if you fancy taking a break from fragging demons in the new Doom, Ahoy's Quake retrospective is an excellent watch.