Harold. The root directory is like the drive designation on your computer, like C: It is the highest level of the drive.
When you add an application a new directory is made and when you run the application it looks for the files in that directory and not on C:
The same is true of the CF card where the camera puts your files. The CF card is a drive and it contains directories where the camera saves the image files. If the files aren't put back in the same directory it came from the camera won't be able to find the files.
When I put the CF card into my card reader my desktop shows the card as Nikon D300.
If I double click the Nikon D300 drive it opens and shows a directory DCIM. This directory is located in the root directory of the card.
If I double click the DCIM directory another directory appears called 100ND300.
If I double click the 100ND300 directory all my image files appear. That's also where your video files should be.