I haven't watched the video, but if it doesn't have anything plotwise, then here's what its about.
In the 70's, a decade after the first Bioshock, the protagonist is the prototype Big Daddy left in a puddle. Splicers have become better and stronger, and a Little Sister has returned from the surface called the Big Sister which is abducting girls to turn them into Little Sisters. Tenenbaum is also part of the plot.