from 123ski in another thread- not sure if this is the optimal method as ive hardly used my gopro yet but it seems like he's on the ball
"You guys are all wrong. both PC and Mac edit the GoPro footage fine. FCP and Premiere Pro will both have problems editing the mp4 files if you shoot in 60fps. The solution is to put the H.264 video files from the camera into a different container.
This will work for both mac and PC.
1. download Mpeg Stream from
www.squared5.com
2. open the .mp4 file in Mpeg Stream
3. click File > Save As
4. change file type to .mov
5. save file
What this does is keeps the entire H.264 movie in its original format, it does not compress or expand the footage. All it does it put the movie in a .mov file container. Once you have done this almost all editing software should be able to edit it without a problem.
quiktime pro should be able to do the same Save As technique, bu Quicktime Pro costs money and Mpeg Stream does not (Mpeg Stream also supports Mpeg2 natively).
Also, make sure you only select "Save As" and not "export As" unless you are trying to compress the footage before you edit (not a good idea)"