Play web videos in Safari on Mac
When you find a video on the web, just click Play 
to watch it. 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. 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.
AirPlay lets you play web videos on any HDTV with Apple TV—without showing everything else on your desktop.
Play a web video with Picture in Picture
Navigate to the web video you want to play.
Click and hold the Audio button in the Smart Search field or in a tab.
Choose Enter Picture in Picture.
Play a web video on your HDTV
Navigate to the web video you want to play.
Compatible web videos have an AirPlay icon
.Click the AirPlay icon
, then select your Apple TV.
For more information about AirPlay, see Use AirPlay to stream what’s on your Mac to an HDTV.