Embed/Linking an option for background audio & Story Map covers

[SaraJL]

Hello!

It would be nice if embedding or linking was an option for adding background audio.

Linking and embedding is always easier to manage than direct uploads! In my experience - it has also be easier for collaborative projects and keeping track of what files are being used in the project. 

I also would like embed/linking to be an option for the Story Map covers.

Thank you!