This was shot at 60fps on a GoPro Hero HD. I conformed the footage to 30fps using Cinema Tools, took it to final cut, did a roundtrip from final cut 7 (slowed the part of the clip down to 10% without frame blending) to Motion 4 (used Optical Flow under the frame blending drop down menu in the properties tab) waited for it to finish (click the spinning wheel to see the progress) and saved it, rendered back in final cut. At first I was having problems with it looking too choppy/strobe-like and too many ghost tales.
Here is what I learned:
1. Uncheck frame blending when changing speed in FCP
2. Save what you do in Motion before going back to FCP
3. When you first start your sequence in FCP, right click the sequence icon in the browser, click settings, go to the render tab, and check "always render at best quality"