[Mindwipe]

The difference is also intent.

YouTube implemented the rolling cypher to satisfy music industry demands that the files were not permanently downloadable (and it appears they were able to provide abundant evidence that Google has communicated that to them in court, I don't think this is a controversial point).

That wasn't the point of the red book spec.

Intent matters significantly, legally.

[hunter2_]

If the rolling cypher they implemented truly exceeds DASH in such a way as to exert control, then I think that would convey intent. If it's substantially DASH alone and DASH requires the equivalent of a rolling cypher just to work, that's rather meaningless; the intent of implementing DASH certainly would've had most to do with adaptive bitrate UX.

Based on some other comments, it sounds like they added something like this for music videos and the like, so it may hold up.

But I'm armchair judging at this point, and IANAJ.

Isn't a rolling code how RF locks (car fob, garage opener, etc.) operate? Those are actually good at keeping out third parties, though.