Flowblade – Free and Libre Video Editor
jliljebl.github.io
jliljebl.github.io
This certainly looks quite professional and polished, but I can't speak for the features and usability compared to other options.
Windows, MacOS, and Linux.
Kind surprising to see them only releasing it on Linux though, considering it's built with Python and Gtk it should be easy enough to build on Windows/Mac. Gtk is notoriously not great on other platforms though, and I assume if it's a team of Linux users building it, they don't want to go to the effort of building it for other platforms, let alone building multiple UI stacks so that it looks good on every OS.
On the plus side, it's open source, so I'm sure they wouldn't object to someone trying to build it for Windows/Mac, submitting a PR, or at least reporting the specific issues that prevent it from working on other OSs. A brief scan through their GitHub requests makes it look like they're not against supporting other OSs, they just aren't interested in putting time into it.
That said, adding things like titles and scrolling credits were unique puzzles.