You don't need to use complex graphics or video motion tools to create backgrounds for YouTube end screens. Instead, you can simply use Keynote and build a single-slide presentation with animation. It is fairly easy to get elements lined up with placeholders and then to play around with various animations to make your end screen look great. Then you can export as a movie and add it to the end of your YouTube videos as you finish editing them.
When you play a YouTube video on your Mac in a web browser you can use keyboard shortcuts to jump around in the video, control volume, go to full screen and turn on or off captions. Make sure you have the YouTube video selected as the keyboard focus by clicking on it before you try to use shortcuts.
The ability to move video into a picture-in-picture overlay with macOS Sierra is a great new feature. However, it doesn't appear to work with YouTube videos. You can get YouTube videos to do this, however, if you know how.
Sharing videos via email, file transfer or using old technology like DVDs can be impractical. Uploading your videos to a service like YouTube that almost anyone can access is easy and useful. You can set these videos to be unlisted or private if you aren't interested in the general publicseeing them. YouTube videos can be viewed on computers, set-top boxes, TVs, tablets, phones. Plus, they can be high definition, giving them a big advantage over DVDs.