In this episode, Tyler demonstrates how to enable audio descriptions for the TV app, as well as for videos on supported websites in Safari on iOS, iPadOS, and macOS. Note that not all apps and websites that offer audio described content detect this setting, meaning you'll have to manually enable audio descriptions through the playback interfaces of such services.
To enable automatic playing of audio descriptions for the TV app and Safari on iOS and iPadOS, go to settings > Accessibility > Audio descriptions, and enable the "Audio descriptions" toggle. To do the same on macOS, go to System Settings > Accessibility > Descriptions, and enable the "Play audio descriptions when available" toggle.