Hey,
Seems like when you do favorite an image activity it creates an album in the user media with the latest image posted on the activity (not really but shows it) and on top of it it in facts has a link to the user_id 1 media set.
You do have the same behavior on your demo site and can see it here: http://demo.rtcamp.com/buddypress-media/members/olivier_lambert/media/album/ it then links to: http://demo.rtcamp.com/buddypress-media/members/admin/media/1/
Thanks for your help, --Olivier