I just got my Hero3 camera a few months ago and one thing I've been wondering is what the .LRV file is for. It's not a file format that I recognize so I'm assuming that it's a proprietary GoPro file.
Help get this topic noticed by sharing it on Twitter, Facebook, or email.
They are low resolution versions of the main video file. You can use VLC to view them.
Install VLC on you computer.
right click a LRV files and click "open with"
Browse to the VLC program directory (c:\program files x86\videoLAN\vlc) for 64 bit win OS.
then click on the vlc application file....you're done.....;-)