A workaround for the time being is to right-click the video and select 'Open Video in New Window'. The video, when playing on it's own in the default Safari video player, does support AirPlay, so it can be watched on an Apple TV. Any subsequent videos will then also play on the Apple TV. However if you navigate away from the video, then you will have to repeat the process as described above.
Please add an option to the video player to support AirPlay if it is enabled on macOS and iOS devices.
https://github.com/silvermine/videojs-airplay
A workaround for the time being is to right-click the video and select 'Open Video in New Window'. The video, when playing on it's own in the default Safari video player, does support AirPlay, so it can be watched on an Apple TV. Any subsequent videos will then also play on the Apple TV. However if you navigate away from the video, then you will have to repeat the process as described above.