download mpeg streamclip
www.squared.com
open that program up
go to List -> Batch List
drag and drop your gopro files into that folder
you will be promted to choose a file format, choose quicktime movie and then select where you want the files to go.
the next window is complicated but you have to do these easy things:
1. in the drop down select "apple intermediate codec" (i believe imovie works with this, otherwise choose "H.264)
2. drag the quality slider to 100%
3. leave frame rate BLANK
4. deselect interlaced scaling
5. the press send to batch
you will be in a new window with all of your clips listed and on the bottom right there will be a
"go" button
When it's done, go to where you put the files and drag/drop them into imovie.
In the future, get your SD card with the raw shots from the gopro on them and I believe you can import them through imove, alot easier.