Replying to GoPro Editing...not working

I probably should check to see threads on the subject but I already started writing so here it goes:

-Just got a GoPro...like every other ns kid

-Got some test footage

-Apparently .mp4 is an uneditable format for Final Cut Express

-Converted it to .mov

-Footage can now be used to edit...but it doesn't want to render...

What the balls do I do? Not super stoked on this conundrum, pretty much the complete opposite of stoked, naw'm sayen brah.

Pic unrelated