I'm happy with instapaper. Even more now that it's independently owned and GPDR compatible. Gladly pay knowing they don't have to sell my data or add advertising to make a living.

bthdonohue.com/2018/11/17/ycombinator-operating-instapaper-through-an-acquisition.html

https://blog.instapaper.com/post/170231611161

Saving youtube (or any other) videos would be nice for offline viewing (train, airplane). I can understand it's not a core feature, would use too much bandwidth and storage on mobile devices.