I don’t have a video, it’s a short section of AEG stock tube that attaches to the gun and then the UBR slides I’ve it, attaching underneath with two hex bolts.
If you order from China, It will take around 3 weeks to arrive. Personally, that’s what I would do, taking a chance on the quality of course, I have done in the past.
I’m replacing mine with a genuine generation2 UBR I have coming from the States.