Some users may see an error when attempting to upload large MTS video files on Windows machines.
MTS is not a common video format, and is currently incompatible with the Windows version of the Video Tool.
As this does not affect many users, we do not have an in-application fix, but we recommend you take the following steps to upload your video:
1. Install a video transcoding app called "Handbrake" on your computer
Here's a link to install Handbrake.
2. Run your video file through handbrake with the default settings to generate a file compatible with the Video Tool
3. Once you have the newly formatted file, try uploading again
If this doesn't work, try uploading from a Mac
Also, in the future, consider changing your camera, its exported video format options, or its recording options to produce a more common file format (MOV or MP4).