Some videos won't transfer from Photos to External Hard Drive
I always back my photos&videos up by copying them to an external hard drive and have been doing this for years. However I'm having troubles now as some videos won't transfer over to the hard drive when I drag them from Photos to my hard drive. It's only some videos, others transfer without a problem. And these are only short clips taken with my iPhone, most of them only some seconds, the longest one probably only 3 minutes..
No explanation pops up or anything, the files just don't move. I've tried different hard drives and it makes no difference.
Any ideas why this is happening?
I'm running out of space on my computer and I don't want to delete anything before I solve this problem.
Oh, I have a MacBook Air, currently using Yosemite version 10.10.5 with 3GB free.
Thanks!
MacBook Air (13-inch, Early 2014), OS X Yosemite (10.10.5)