There is no video or manual but it's not too difficult to install.

The little "lever" on the back can be unscrewed counter-clockwise and there is a small grub screw (Metric inbus) inside of it. Screw that out to make the dial come loose from the backplate.
Careful, there is a spring and ball underneath to keep the position of the selector locked.
The stave goes from the inside to the outside via the screwhole on the back of your bbu. Then put the dial back on (up or down, whichever you prefer) and put the grub screw back in, then screw the lever back in. Done!

Very sturdy.