Repair Gopro files

I read a couple of place that i am not the only person who this trouble occurs. 1 time on 5 my video are corrupted on my gopro. It's always appen if my gopro miss battery, so my video file as seen not be writed correctly on my SD card.

I can't find any tool on gopro website, i found a tool who it's seen working, but it's ridiculous to pay to correct my gopro video files.

http://grauonline.de/cms2/?page_id=5

Actually i am frustred on Gopro because they don't relase a software to repair they own video file.

Anybody have a solution for my trouble ?