In practical terms, DRM obviously can be made to work.
People ideologically opposed to DRM tend to have two blind spots about the DRM service model.
First, they assume that DRM users demand that DRM prevent any copies being made. But that's not true: obviously, any video you show a user in the privacy of their home can be cam-copied. It has even been the case (though it will be less and less the case moving forward) that you could obtain a high-fidelity digital copy. DRM users have always understood that to be the case; what's important is not that copies be impossible, but that they be difficult for ordinary users and, ideally, incur a quality hit. If copies are inconvenient and/or of lower-quality, most of the market will pay for legitimate copies.
Second, and more importantly, DRM opponents assume that the restriction DRM users are seeking is indefinite. But for the most part, content owners are much less concerned about long-term restrictions than they are about the new-release window when their content is most in demand. A DRM scheme only has to survive for a couple weeks to generate immense value for content owners.
From a security and cryptography perspective, a scheme that can be resilient against expert adversaries for a few weeks, or even a framework for minting such schemes on demand, is a commercially reasonable proposition.