I was in the area shown in the video, and firstly I found the door opened and I crossed it. I was activating the red gears, and I think I blocked the entrance, but then I died where it's shown at the end of the video, where the bag of guts is. I can't find a way to get in this area, and I believe it is necessary to progress the story,
#Getting stuck on old town
sacred pawn
grizzled sand
It's actually possible to just shoot the red gear through the gate with the shotgun, since that's what I always do I'm not too familiar with the gates around that place