It's not that simple to see in person without some kind of chemical tests to make sure what type of steel it is.
What Bike Mikes tests shows is, the watch case isn't 316L at all. Unless tested we simply dont know what the heck type o steel the reps are made off.
In short, Bike Mikes test shows that an (in his test case rolly) rep is assembled from parts, probably from different manufacturers, using various types of steel to manufacture.
Considering the shade/niche of the rep biz it most is likely they will use any type of steel to get the final product out that makes the money regardless...