SUNSCREEN in UV

I'm confused by this video. SPF is a measure of duration (indirectly). SPF 100 doesn't protect against instantaneous sun exposure much better that 50 SPF, if at all, but it can do it longer. This is pretty clear just by reading the FDA's website on SPF. If you compared 50 to 100 SPF (all else equal) over a period of 15 minutes, protection is close to identical, but over 6 hours the 100 SPF outperforms because it can absorb more total solar energy. This seems logical, as the sun only produces so much energy - once you cross the threshold of how much energy is incoming, you can't get much better protection. That said, the protection/duration is not doubled, as the value is exponential. Typical SPF tests last 4, 6, or 8 hours, and measure how much UVB is not blocked. QyetOne summarized this below, but here it is again. 
SPF 4 = 1/4 or 25% of the radiation is not blocked (absorbed/reflected)
SPF 8 = 1/8 or 12.5%
SPF 15 = 1/15 or 6.7%
SPF 30 = 1/30 or 3.3%
SPF 50 = 1/50 or 2%
SPF 100 = 1/100 or 1%
SPF 150 = 1/150 or 0.67%
So the incremental benefit of higher and higher SPFs decreases. Of course, once you get above 50 or so, correct use and personal characteristics are probably more important than the SPF (coverage, reapplication time, skin type, sun intensity, etc.) for most people.

Also, FDA is the Food and Drug Administration, not the Federal Drug Administration.