stream video (Apply TV ) from MacBook Air via AirPlay

Read here: Use AirPlay to stream video or mirror the screen of your iPhone, iPad, or iPod touch - Apple Support

- Use in-app ‘basic’ AirPlay from Safari, QuickTime Player, the TV app, or the iTunes application,

- or use screen mirroring using screen capture (any app).

If screen mirroring or streaming isn't working on your AirPlay-compatible device - Apple Support

Some apps or services may not support AirPlay or screen capturing.

What is your model Apple TV, and its version system software? Identify your Apple TV model - Apple Support

What is your model Mac, and its version macOS? Identify your MacBook Air model - Apple Support