Thank you for clearing up this answer for me as well. I now know I have done everything correct when setting up my WordPress site to use Media Library Assistant, but it is still not working 100% correctly.
If I perform the above actions you just listed to be able to allow for the custom taxonomies to appear in the media library backend for sorting and such, it does not work.
If I enable Taxonomy Support in General Settings, for both Categories and Tags, they do indeed display under "Screen Options" under my Media Library backend.
However, there are two problems I am having still:
1. Att. Tags, and Att. Categories will not show up under Screen Options just like the default categories and tags do.
2. There are no options for Bulk Tagging or assigning of Bulk Categories in the Media Library backend yet like your above post described there should be.
I am running a clean install of WordPress 3.5.1
And Media Library Assistant 1.30 at the time of this post.
If you have any idea what could be causing this problem any thoughts would be great!
I would also be willing to setup a publicly accessible installation with this problem to demonstrate it to you if you would like to look closer.