That might've been the wrong video. They have a few of them on live sand...I was trying to answer the why do they sell live sand part of your question.
In one of the videos Ryan explains that one type of live sand is covered in live bacteria while other types are seeded with dormant bacteria that become live once the right conditions are met.
Personally I have used live sand in all of my saltwater aquariums to date and I did not wash any of it beforehand. This made the water cloudy for days. If I had to do it over again, I would definitely wash it to remove all the fine particles before adding it to an aquarium and then add a bottle of live bacteria afterwards to get things going.
My personal opinion is that it is a gimmick to get more money out of people. Even knowing this I still buy it because I like the particular look of the Ocean's Direct sand.