The 7D cameras will never mount on the desktop, so you will need to use an application such as Image Capture , Photos  or iMovie  to extract the footage.

1. To export the footage, make sure that the camera is Turned On and set to View Images. You will also need to Connect the camera to the computer using a Micro USB data cable.
    
2. Normally, after you connect the camera, Photos  will open Automatically. To Import using Photos , select the images/videos you would like to Download and click Import Selected. If you wish to download Everything, click Import All.
   
    
3. If you wish to save the photos/videos to a Specific File, you may wish to use Image Capture . Begin by opening Image Capture .
    
4. You will then need to select the correct Device from the list in the Left Hand Corner.
   
    
5. Select Where you would like the images to be Saved by clicking on the Drop Down Menu at the bottom of the window.
   
    
6. Highlight the images/video you wish to Import, or you can select Import All. Click the respective button.
   
    
7. Your media will now download to your chosen location, and when the file has been copied across, a green tick  will appear next to the media item.