On a computer? Use the Cast button that appears on the video player in Chrome to stream directly to a Chromecast or Cast-enabled TV.
On an iPhone or iPad? Tap the AirPlay icon in the video player controls to stream to an Apple TV or AirPlay-compatible TV.
On Android? Use your phone's built-in Screen Mirror or Cast option in the Quick Settings panel to mirror your screen to a Chromecast or smart TV.