It seems as though I have little to no braking power in the rear. See attached video:
https://imgur.com/a/k9cxjVb
I bled the brakes, and the pedal seems to have gotten better (doesnt go to the floor as much) but the brakes barely hold the car. Stopping power is very very poor. It also seems the rear brakes aren't doing anything.
I already pulled the drums and everything looks good/fairly new too. Any ideas? Master cylinder doesn't seem to be leaking externally.

 

Sounds like air in the master cylinder.

What happened when you removed it and bench bled it, as is required in these cars?

 

I didn't bench bleed the master, i only bled from the actual brakes. I guess I will try bench bleeding the master next

 

You MUST.

With the MC at the angle that it is in our cars, and the exits from it to the bleeder screws (the line fittings) BELOW the air pockets, there's NO WAY IN HELL for air ever to get out any other way. You can run a gallon of fresh new brake fluid though it EVERY DAY, and even TWO gallons on Sundays, and that air will STILL ALWAYS be trapped up there.

Only way to ever get your brakes to work right is to START THERE.

 

I have read that you cannot do the "bench bleed" on the car because of the angle that the MC sits at.
A bench bleed would position the MC level.
Apparently, an air bubble gets trapped in the MC that can only be bled out with the MC level.
Maybe the back of the car could be jacked up a couple of feet...…………..?

Sofa beat me to it.

 

damn, I must have a **** ton of air in the system because when I bled the brakes, some air bubbles did come out. How would I go about bleeding the master cylinder?