In a dream scenario, Hazel would just support YouTube uploads. That would solve my problem. But since it doesn’t, is there any other way to automate uploading a file to YouTube with a watch folder?
I need to look into this too. There is a post about it on the MPU forum which I have saved to take a closer look at; the answer there may (or may not) be of some use:
Google have also published an example Python script for uploading YouTube videos.