I created a simple Automator application to quickly add video files to iTunes.

Open Automator and drag the action "Ask for Finder Items" to the workflow pane. Select "Files and Folders" next to Type and put a check in the box in front of "Allow Multiple Selection".

Ask for Finder items

Next, drag "Add Any File to iTunes" from the action column to the workflow pane, under "Ask for Finder Items".

Add any file to iTunes

Save your workflow as a Finder plug-in.

Save workflow as Finder plugin

To use your new Automator application, right-click on any Finder window and select the application from the drop-down menu next to "Automator." In Mac OS X 10.5, select the application from the drop-down menu next to More-->Automator.