Videos from iPhone imported into iMovie and turn green.

When I import videos from iPhone5s into iMovie '11 on my Mac, they turn green. This only started happening after I upgraded to El Capitan.

This does not happen, by the way, with videos I created using apps like Cinematic. It ONLY happens when its just the regular video camera on the iPhone.

How can I fix this? I wish I never upgraded to El Capitan. Everything is messed up.