I want to make VLC my default player on Mac OS X 10.10.3
Right click on any movie file you have.

Get Info

At the bottom of that window you will see the current app used to open it.

Change to VLC and use the "Change all"

 

You need to repeat that for all movie files that have different extension.

Normally you would have .fvl, the .mov, and maybe some other formats.