You may know that with some videos you can view them in picture-in-picture mode on your Mac. A video from vimeo, as an example, will have a small icon representing picture-in-picture. When you click on it, the video will float above all your windows and move to a corner on your Mac, thereby allowing you to view the video while working. You can resize it and move it to a different corner just by dragging it. I use this quite a bit.
But did you know you could do this with YouTube videos too? You can’t do it by finding an icon nor by control-clicking on it (holding down the control key and clicking on it). So how do you do this? You need to control-click on it twice, yes, two times. When you control click on it a second time, you’ll get a new menu with the picture-in-picture option. Select this and your YouTube video will pop out above all your other windows and move to a corner on your Mac. So the next time you want to watch a video from YouTube on your Mac, control-click on it twice – and keep working. :)