Does "BuddyPress Media Photo Tagging" works with NextGen gallerys?
Sorry for such a long delay in reply from us. 
Answer to your question:
the photo tagging add-on do not support NextGen gallery.
But we will update our add-on which work with all the photos which are uploaded in WordPress. Hopefully it will be done very soon.
Thanks,
–Nitun
Dont worry. Do you have an estimated date for the update launch?
We don’t have estimated date for the release but when we will update you once we are done with this feature.