First, never save files / folders on the desktop the access permissions may be such that it stops the program accessing the files, in particular if the new laptop is running Windows 8 and also cause problems with long filepaths if the directory structure has many levels and long titles.
In your Documents folder you should find a folder called Magix Projects (or Magix) - if not create one then create a new folder within this one. Move the video files to this folder. They should then get all the correct permissions.