Restore bathtub enamel?
I did not watch the entire video but have had my tub repainted. What they probably don't tell you is that you are supposed to completely dry the paint after each use. A pain! So most people don't do it , leave the tub very and afterwards have a peeling paint job in just a few years. I managed to make my last for 10 years, but I got tired of the drying. I've heard there are new paints. I personally would investigate tub liners, unless they offer a really long warranty on the paint.
Btw, diy paint kits are a disaster waiting to happen, IMHO.