Stop media compound objects

[dcnb]

Pull request

Proposed changes

This revision stops video/audio/youtube/vimeo when the user clicks the next button, the previous button, or close button on a compound object modal.

I've also added a test demo metadata that includes all media in one compound object. I'm assuming we'll delete that once this PR gets merged but thought it might be useful for your reviews, @owikle and @evanwill

Types of changes

• [ ] New feature (non-breaking change which adds functionality).
• [ ] Enhancement (non-breaking change which enhances functionality)
• [x] Bug Fix (non-breaking change which fixes an issue).
• [ ] Breaking change (fix or feature that would cause existing functionality to change).

Checklist

• [ ] I have read the CONTRIBUTING document.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.

[dcnb]

Also this line:

• [ ] I have read the CONTRIBUTING document.

doesn't properly link to that document

[dcnb]

@evanwill your review is requested ...