Here’s something to try with your Shield.
You can record what is showing on your TV screen by long pressing the home button on your Nvidia remote and click on record. Do the same to stop recording. The recording was stored in my X-Plore app under movies.
The instant replay feature does the last 5 minutes of what is playing and saved in the same folder in X-Plore.
The Screenshot will take a pic of what is on your screen at the time you click it. It is stored in pictures in X-plore.
All the other stuff there is for use with Twitch, and I have no idea about anything Twitch.