You can BTW buy pre built devices where this is already done from owncloud I believe.
It doesn't bother me that people pay other people to do things, no need to be condescending about it. What bothers me is when people are funneled into paying for services that are more stressful to use than doing things themselves, and then making excuses for the state of affairs for whatever reason (either they're convinced by the marketing, or their salary depends on it all continuing this way).
People by and large use what they see in advertisements and justify the decision after the fact. What is preferred is not always what is superior.
Bandcamp is as easy to use as Spotify. Yet people don't use it as much. Why not? Marketing is why.
Mobile UX is full of deliberate friction points put in to support profitable business models at the expense of utility. The mobile experience is designed to funnel users towards making certain choices. This is beginning to happen in windows as well now. And people just go with it.
Is it condescending? Maybe. But if I was wrong you wouldn't have advertisements on TV, marketing people know what works and businesses aren't in the business of throwing money away for no return. People wouldn't bitch about Facebook and continue to use it, they'd go somewhere else.
As for your reference to ownCloud, there are no pre-builds for raspbian. You have to build the web stack on the pi. This is the most inconvenient option imaginable, but I guess it's the hypnotising marketing stopping Grandma from building a web service.
Needs to be very simple so my grandmother can build it, and cheap. No maintenance, set and forget. I assume there will be apps available for all her devices to quickly go through the process or will she need to create them? It needs to be easy to search for content and stream on any device at any time without fail.
She doesn’t care about ‘owning digital movies’ or the exaggerated threat of her accounts being closed. She's is much more likely to accidentally lose her own content managing it herself. She just wants to watch movies, how much will it cost to own all that content? Less the $10/month?
No professionals so let’s keep instructions basic and preferably just using a single blank drive with no content.
It must bother you that people don’t grow their own food? That they can’t manage their shit and need to buy it from a store?