Miracast is, at best, an iffy protocol, but when it works as intended, it lets you mirror your Android phone or Windows PC's screen on your TV in real-time. Roku has a screen-mirroring protocol in a sort of perpetual beta, and as such, it works about half the time. Here's how to play with it.
1. Access the Settings menu.
2. Select System.
3. Open Screen Mirroring.
Make sure that "Enable screen mirroring" is selected.
4. Cast your screen from your Android device or Windows PC.
Generally speaking, you can do this from Android devices by selecting Display > Cast Screen in the settings menu, while you can accomplish the same thing from the Devices menu under Settings in Windows 8 and 10. Check our how-to for more details.