Camera Stream audio continues to play when macOS app window is closed

**Device model, version and app version**

Model Name: MacBook Pro (13-inch, 2018, Four Thunderbolt 3 Ports)
macOS Version: 11.0 Beta (20A5395g)
App Version: 2020.7 (7)
Safari Version: Version 14.0.1 (16610.2.8.1.1)

**Home Assistant Core Version**
Home Assistant 0.117.0.dev20201017

**Describe the bug**
Noticed something weird while setting up and testing a new RTSP camera. I had a camera stream opened (more-info dialog) and when I closed the macOS app window, it continued to play the stream (at least the audio portion).

When I clicked the app dock icon expecting to close this more-info dialog, I discovered that the dialog was _already_ closed (nothing visible on-screen), yet the stream was still playing in the background for some reason.

This only seems to occur when using the keyboard shortcut (cmd-w) or menu bar (File->Close). If I click outside of the dialog using the mouse to dismiss it, or press the ESC key, it properly closes the stream.

**To Reproduce**
1. Open a camera stream with audio playing
2. While this stream is active and playing, close the macOS app window using cmd-w keyboard shortcut or File -> Close in menubar
3. Stream will still be playing unexpectedly

**Expected behavior**

**Screenshots**

**Additional context**