I'm trying to replace a shower cartridge to fix a low water pressure issue in my mother's house. There are no brand names to google and I can't check for a clip to remove because I believe the bezel is stuck. Any ideas? I took a video so check this link for a better idea. Tonight I'm going to take a huge wrench to it and try to unscrew on the inner pipe bit where it looks like there's a spot to grip it
I just looked at the video again. Although it's jumping around a bit you can see the flat edges of the brass fitting so it can be gripped with a wrench or channel locks. I would spray it good with WD40 and put channel lock liers on it to turn that fitting.
To be on the safe side you will probably want to secure the valve body with a plumbers wrench while you unscrew the fitting counter-clockwise with the channel locks. That will keep you from putting excessive pressure on the plumbing fittings.
Once that fitting is off you will have access to the cartridge.
Again, make sure you turn off your water supply first!