I cannot play any of my videos?

I've had my Macbook Air for about 3 ish years now, the only things in my photo library are all pictures and videos taken on my iPhone. I had a 6 but recently upgraded to an 8 plus. When I click on any of my videos it says "Photos cannot play this video because resource is unavailable" or "An error occurred while downloading a larger version of this video for editing. Please try again later." I updated all my software to the most recent High Sierra version. These problems with my videos started occuring when I started to use iCloud. I couldnt just watch my videos anymore, they all took a very long time to load. I stopped iCloud and now my videos are just not working at all..