Snapchat videos won't import into iMovie because they're "hidden"

I'm working on a project in iMovie and all of my content is in the Photos app. I can import some of the videos, but anything that was saved into Photos from Snapchat can't be added to the project for some reason.

All the video format seems to be fine but I thought I would try a file converted anyway. But then when I try to export them from Photos, they disappear. If I drag it or export it to a empty file on my desktop, it appears for a second then disappears.

After trying everything I could think of to find it, I try editing it with QuickTime and then saving it, when I get this message. Even if I remove the dot, it says "The operation could not be completed.

I have no idea how to resolve this. Maybe changing the file names of the videos, but there doesn't seem to be a way to access the actual files in Photos (which is extremely annoy but that's probably another issue). Any help would be very much appreciated.

I'm running High Sierra 10.13.5, MacBook Pro Retina mid 2012.