Update [10/2/2016]: It appears that Google has finally put a stop to this trick.
Imagine you want to use a QR code so guests at Parents’ Night can scan the code and stream video or audio straight to their mobile device. If you share the files in Google Drive, users will be taken to a Google page where they have to download the file first. But if you can create a link that points directly to the file, users can access the content right in their mobile browser.
Turns out you can do this while still using Google Drive. Any public folder in Drive can host files and provide direct links to the files.
How to create the hosting URL:
This will provide a folder that will give direct links to files inside the folder.
Note: hosting view will not display files created in Google Docs.
(Google hosting view)
(Google Drive View)
Once in the hosting folder, you can right click on any of the files to get a direct link to the file.