It's proprietary and the free as in beer version is limited to 720p mp4 ("YouTube") export, which was sufficient for my use case.
The tool started to work on color, but it looks like they've made a decent editor also.
The content was super important stuff - early footage of many areas of the world not otherwise filmed - and was destined for Wikimedia Commons.
It was the worst experience I've ever had with commercial software since Windows 'corrected' an NTFS volume in ~2005 and nixxed the lot. From memory it was something to do with the input codec (beyond my control as lossless was a requirement), the output codec, and the aspect ratio. The software just couldn't cut the stuff. I was left to go back to ffmpeg and VLC. I will never again waste time learning a commercial UI.