Looking at the screenshots, you have created a Service Account. Service Accounts use two-legged OAuth, and therefore do not have any user-consent-and-redirect dance.
A Service Account would not have permissions to videos in your personal Gmail account. Maybe that's OK, maybe it isn't. It depends on your use case which you don't describe in your question. If you need your application to act with the same permissions as your Gmail account, you'll need to use a slightly different technique. (described How do I authorise an app (web or installed) without user intervention? (canonical ?) and https://www.youtube.com/watch?v=hfWe1gPCnzc)