I can feel your frustration with the service but I'm unconvinced that "download the next ep" is a dark pattern and more that you're a niche that their UX currently isn't catering towards.
I do a lot of cellular/tethering and know some of the pain points but can recognize that the needs are quite different to the regular user who may consume stuff at home then want to take stuff with them on the go.
Normally I see that UX often caters to the lowest common denominator which leaves power users and niche users sidelined.
My personal bug bear on this subject is that YouTube no longer buffers entire videos and holds them there - presumably this saves them lots in traffic costs and additionally allows them to up sell YouTube premium
Sorry I didn't see this immediately, I don't think that downloading the next episode is a dark pattern in and of itself. But I do think downloading the next app over mobile when the description explicitly says it wouldn't is questionable. And I think deleting downloads automatically without any good reason is so far removed from assumed functionality of a download to be a borderline dark pattern.
Without the "Smart Download" enabled the episodes persist until I delete them or cancel my service, that's the assumption with a download. Smart download immediately deletes whatever you downloaded as soon as it sees fit - which in my case was erroneously assuming I was on wi-fi. And this was my first download, it's not like it had some storage space restriction to deal with. I had ~16 GB free and it was 100 MB.
The next episode feature aside, it seems weird to say, "Okay, download this one" and then it saying, "Okay, so you meant download it and then delete it".
And to your Youtube point, I think it depends on the use-case. I fully agree with holding the buffer there, but if I'm on mobile data, I might not necessary want it to just load as much as it can as soon as it can because I pay per MB.
I do a lot of cellular/tethering and know some of the pain points but can recognize that the needs are quite different to the regular user who may consume stuff at home then want to take stuff with them on the go.
Normally I see that UX often caters to the lowest common denominator which leaves power users and niche users sidelined.
My personal bug bear on this subject is that YouTube no longer buffers entire videos and holds them there - presumably this saves them lots in traffic costs and additionally allows them to up sell YouTube premium