Your typical Let's Play has commentary and gameplay. This is not your typical Let's Play.
Niconico user Furu Terrazzo was playing through Silent Hill 2, but due to a recording screw up, he ended up only with the voice file but lost the visuals. So, instead of simply doing it all again, scrapping his work, he decided to draw the parts of the Let's Play that he lost. He starts off the clip by very quickly stating what happened and apologizing for the snafu!
The other Let's Plays aren't like this and have standard game footage. I quite like this mix of drawings and gameplay. This isn't a first time for Furu Terrazzo. Previously, he drew pictures for a Shadow of the Colossus stream he did a few years back. Here's Shadow of the Colossus. (The Let's Play starts at about 40 seconds in.)