Add a separate download button, to download a map without storyboard, if it has one
Knowing my own experience, some storyboards can be very big in size (25+MB) and for users who plays with 100% BG Dim and Storyboards/Video off, this will be just a deadweight they'd never look at. So why not add a similar to "Download without video" button that can download the map without any storyboard?
Basic design proposal
P.S. In case with video/storyboard I can't think about good way, since you either have: A. Download with sb/vid and that gives an issue where you get video, you don't want to use (so deadweight again); B. Make separate buttons and that makes the layout look cluttered
If anything, this should be combined with the no video option.
I don't mind this approach