But it's never, ever, necessary, not when gazillions of scene groups strip DRM from a work and upload it as soon as it hits the market, if not before; sometimes they just get hold of the studio version. It might make some obscure video games harder to pirate, since it's much harder to strip DRM from code than from data, but video? No way.
DRM makes it harder for me to put legitimate content on a device I own, but it makes it no harder to pirate that same content.