Play web videos in Safari on Mac
With Picture in Picture, you can play a video in a movable window that “floats” on top of everything else, so you can always see it, no matter what you’re doing. With AirPlay, you can play web videos on any HDTV with Apple TV 4K — without showing everything else on your desktop.
Play a web video with Picture in Picture
Go to the Safari app
on your Mac.Go to the web video and begin to play it.
Click
in the Smart Search field, then choose Enter Picture in Picture.Click
to go back 10 seconds. Click 
to skip forwards 10 seconds.
You can drag the window to any corner of the screen and the window stays put, even if you switch desktop spaces. You can resize the window to see more or less of what’s behind it.
Click 
to return the video to the original window and continue playing. Click 
to return the video to the original window and pause playing.
Play a web video on your HDTV
Go to the Safari app
on your Mac.Navigate to the web video you want to play.
Compatible web videos have an AirPlay icon
in the video controls in the bottom of the video window.Click
, then choose your Apple TV.
See Stream video and audio with AirPlay.