I feel like in that video they actually sanded the car lightly, then shot the video of it's Before condition, then completed the wet-sanding and polish. It was just too consistently and evenly swirled over the entire paintwork - without major defects in the paint itself - to have been that condition without deliberation.
Wet sanding, to my knowledge, is only appropriate to remove orange peel from excessive clear coat or to remove burns in the clearcoat. It is a specific technique to rectify gross un-evenness in clearcoat. It will not address actual paint damage, peeling clearcoat, and many other flaws.
Almost any paint job where the paint is in decent condition and clearcoat exists on top of it can be made to look nearly showroom new with about 8 hours or less of work. (there is a difference between "showroom new" and "concours ready").
A perfectionist will remove trim, tape off edges/plastics, etc.
However, a really excellent detail can be had by simply going through 2-3 stages of polishing with appropriate technique, pads, and products - avoiding edges and trim without taping them off/removing them - and then appropriate sealant/wax application.
I can do a wash, clay, 2-stage polish (medium and fine), and sealant in about 4 hours and I'm no where as fast as a pro.
Joe
P.s. I too have found BMW's clearcoat to be admirably tough. On Carbon Black, my 2-stage polish in 2012 removed probably 60-70% of the swirls/clearcoat marks in my paint. A recent professional detail removed about half of the remaining marks (it was a $150 exterior-only detail by a pro shop). So depending upon condition of paint, you might need an aggressive compounding or you may need to do 1-2 more passes.