Storage- "Frames" taking up space
So, I just updated to macOS Sierra and LOVE it- mainly because of how it actually helps you get rid of unnecessary storage clutter. Under "Manage" and then "documents", I notice that there are a ton of documents, each called "Frame 14336 - 15359" each with a different sequence of numbers at the end. They seem to take up a lot of space on my mac but I don't know if it's safe to delete because I don't know what it's for, so I'd just like to know if it's okay to delete.
If it helps, I have Office 2016 installed on my mac as well as Final Cut Pro X and Motion.
MacBook Air, macOS Sierra (10.12), 2015, 11.6 inch