Changing duration of multiple final cut pro clips
I'm sure you've run into a situation within Final Cut Pro where you want to have a preset duration for all of your clips. It can be frustrating having to load each clip into the Viewer window and set in/out points for the required duration.
Fortunately, you can use a combination of the 'edit selection tool' and the 'extend' function to create a timeline that includes all your clips at the specified duration.
Since this tutorial does not require audio, disconnect the source audio patches in the timeline window for your sequence.
Next, select all of your clips within the Final Cut Pro Browser window.
Drag all of the selected clips from the Browser window directly into the Canvas window. Drop the clips off in the box labeled 'Superimpose' This will superimpose all of the clips on top of one another in the Final Cut Pro timeline. 
Now click on the 'edit selection tool'. It's right below the 'arrow' tool. The 'edit selection' tool will allow you to highlight any edit point. You can select multiple edit points as long as they are on separate tracks.
Now go ahead and select all of the edit points. Make sure they are all highlighted. *Also, it is important that you park your yellow position indicator at the end of the shortest clip. 
With all the edit points highlighted, press the 'E key (extend edit). This will trim all of the clips to where the position indicator has been parked. *There is one catch! If your position indicator is parked beyond the shortest clip, the may not be enough media for one or more clips to be extended. This will prevent the extend function from working. All of the clips must have sufficient media to be extended, or the extend function will not work. 
Ater all of the clips have been extended, you can always select all of your clips and right click on them to change their duration.
