This just looks like you have changed the file association for that file type to another program. See my screenshot where I have changed the association for .mp4 to Alley:
- .mp4 set to Alley, .mov set to VLC
- file association.PNG (27.78 KiB) Viewed 3296 times
You can easily change this back by right clicking and picking open with->choose other then selecting the always open with this app/program checkbox.