I haven’t seen that particular video, but I think I know what goes on. I suppose that the guitar is painted with an opaque or at least tinted lacquer. If so, the paint will cover or obscure the binding, and the whole idea of a binding for decorative purpose is ruined.
This is how I do it. I shoot a thin layer of paint and wait until the paint it dry to the touch but not very hard. I use a razor blade for scraper. I give the blade a "hook" by running it at an angle against a screwdriver or something similar. I hold it between my thumb and index finger and use my thumb nail as a depth guide. Using light touch, and paying attention to not removing to much I crape away the paint. If needed, I shoot a new layer of paint and repeat the above. NEVER shoot all layers of pain before scraping. The paint will be too hard, and chipping of the paint WILL occur (been there, done that).
Please note that if you spray on several layers of paint before the clear, you will have to spray a lot of clear, sand back lightly, spray more and so on to be able to get a smooth surface.