Hi Fourmica,
We're glad you're enjoying everything, except for the video downloads.
You are correct, at this time, downloading videos is only supported on desktop/laptop and is not supported on phone or tablet due to wide variations in their storage capabilities.
Bringing download support to the app/mobile devices is something that is under consideration with our developers and we'll definitely pass along this feedback.
If you have any questions, comments, or concerns, please contact us.