iMovie OBS/Videos are choppy

I use OBS for recording my screen and when I export it, it converts to .mov . So when I import the video into iMovie the quality is only clear when the video is paused. When the video plays, the quality is terrible and drops frames. Also when I upload videos I have imported from my SD card, the videos are really choppy and when I use the rolling shutter to try and help it, it does work. Please help, I just want to edit videos

My Mac Information:

Mac (20-inch, Mid 2007)

2 GHz Intel Core 2 Duo

I am also using iMovie 10.1.2