1. Enter Kazam in Ubuntu Software, you can not find this software, just click install
2. How to use:
Select Screencast
Fullscreen (full screen) ----- Windows (window) -------- Area (area),
Then click Capture to start recording.
3. Stop recording
There is a Finish recording in the upper right corner
4. Then click Continue to save the recorded video in the folder you want.
5. Download MP4 Player
sudo apt install smplayer
Then you can play your recorded video.
Under Windows, you have to use players such as Tencent Video to play. Below is the animation I recorded with Screen To Gif: