Aswin Anand

With this plugin, assigning multiple categories to one or more posts is a 
breeze. Pop the plugin’s PHP file to your wordpress plugin directory, 
activate it and click on “Assign Categories” under the Manage menu. 
The page will show the list of available categories, followed by the 
available blog posts. You can select the categories, select the required 
posts and then click on “Assign Categories” at the bottom of the page. 
Now, all your posts will be assigned the new categories.
Plugin Page: <a href="http://www.aswinanand.com/2008/10/bulk-assign-categories-to-multiple-posts/" rel="nofollow ugc">http://www.aswinanand.com/2008/10/bulk-assign-categories-to-multiple-posts/</a>

Assign Categories

Assign one or more categories to multiple posts in a single shot, with or without preserving existing categories.

Ahir Hemant

Taxonomy In media Library provides better support for media and attachments in WordPress.

My Media Category

Taxonomy In media Library provides better support for media and attachments in WordPress.

Assign Categories vs My Media Category