3. Change the media type within the field "Media Type" for each / multiple files by using the drop down box
Just to clarify, for those less familiar with the interface, the drop down menu is not immediately visible. After adding the column, do one of the following to go to 'in-line edit mode' and make any desired changes:
1. Right click on the media type value and choose rename from the menu.
2. Slow-double-click on the media type value.
3. Click on the media type value and then press F2.
Either of those 3 methods will place the column into what's referred to as 'in-line editing mode'. After making changes, press enter or simply click away from the edited item to apply your changes. Subsequent presses of the Tab key will move the editing focus to the next (editable) column on the right, while Shift+Tab will move the editing focus to the next (editable) column on the left.
-marko.