Under the hood there is a plastic tag with a picture of a fire helmet on it strapped to a wire. I believe this shuts off the 12v system and therefore deactivating the 400V system as well. Correct me if I'm wrong anyone.
There are two "cut loops" in a newer Model S vehicle. The first, as noted, is the fireman's loop under the hood. Pull the tag out, cut the loop in two places (cut a segment out). The second is behind the rear driver's door - open the door and with a circular saw cut through the body about 1.5-2" deep along the line indicated; this will disable the contactor and safety systems as well. Older cars do not have this second loop.
The other thing that first responders need to know is not to use the outside door rail as leverage for a dash roll because of the high voltage cable routing; in older cars, the DC-DC converter placement needs to be considered.
The First Responder's Guide (linked above) shows the location of the airbag inflators (responders want to avoid these too when performing extraction).
The first video (sad to watch, they destroy the car) is a good video but is based on the first-generation Model S, and quite a few things have changed since then - so make sure they look at the guides and PDF's (they're up to date).
