This is a gif that shows a person mounting a strip along the inside edges of a frame when making an infinity table led mirror. The frame is wooden, with a piece of dark glass. The person is taking an LED strip embedded with little metal studs or dots, and is lining the strip along the inside borders of the frame. The strip appears to have an adhesive on the back. The person has one side of the frame and is working on the other.
Check out the tutorial:
How to make an infinity table