I tried make a screen recording today with the 'screenshot' utility, but it stopped working (message: "You can’t open the application “Screenshot” because it is not responding."). Restarting my iMac didn't solve the problem. I'm using Mojave.
You could try to restart in Safe Mode and see if Screen Shot works in Safe Mode.
Use safe mode to isolate issues with your Mac - Apple Support
You could try opening Activity Monitor in the Applications Folder/ Utilities Folder. Type "Screen Shot" in the search box. Then click on the "X" at the upper left of the Activity Monitor window. Then click on "Quit".
Thanks for the advice. It helps in closing screenshot, but when I restart it, I can click "record" but then it doesn't respond anymore, ie it doesn't record and when I click on the screenshot icon again, the message that it doesn't respond re-appears.
Screenshot utility not responding
