Sounds like a brake shoe dragging against the drum (or other hdwe. inside).
Hard to tell the exact noise or volume of it through U-Tube, but that's what the video sounded like to me.
If you did it & are familiar with the hdwe. holding the brake shoe in place you might be able to tell if one of the pins is loose/missing from the back side. (I'm referring to the pins/spring/washers that hold the shoe against the backing plate)