If you want a quick way to save a video from the simulator, you can now write this on the command line:
xcrun simctl io booted recordVideo --codec "h264" --mask black --force ~/Downloads/Simulator-$(date +%Y-%m-%d_at_%H.%M.%S).mov
Then use the simulator as normal, and when you to finish the recording just press
Crtl+C on the terminal.
You will find your video in the Downloads folder.
Note: This only works with Xcode version 11.4 and above.