Unless you have a miraculously soft landing, you can still expect a big banana bruise and several days of soreness if my friend's unplanned test was typical. Not that my butt has any armor, but a hair misleading.
Professor Bumblebee can probably explain how in these demonstrations the weight is distributed over a large area for minimal friction, how the shock load was minimal (
kevlar is not too stretchy, so fibers break when getting a nice tensile load due to the higher static friction coefficient...) etc.
Still beats plain denim though.
