Google has picked up speed in the past few weeks when you look at the news about Stadia like this. They seem to have realized that the start was not well received and that you have to do a little more to keep the community happy.
If you should also use the streaming service on your Android smartphone or tablet, you may have noticed that nothing happens or an error occurs when you press the capture button. Google has now fixed that. If you press the button briefly, a screenshot will be taken. If you keep the button pressed, then you record the last 30 seconds of the playing time in a short video. The machinations will then end up in the recordings in your Stadia account as usual.
Now all Google has to do is make the Assistant button work on Android.
