capabilities of extension and host app

I know if you want to play a video in picture in picture mode you have to enable the background mode to achieve it.

But I found when I made an action extension (you can't add background mode to an action extension since there is no this option in its capabilities page),I can still play a video in picture in picture mode using the action extension.

Why is this happening?Does the extension share the capabilities of its host app or its containing app?Thanks!

capabilities of extension and host app
 
 
Q