6.1. Firstly power on the mini PC and enter Ubuntu system --> connect to the internet via WiFi or LAN from USB (LAN would be much faster than WiFi), --> click mouse left key at top right corner of Ubuntu account and choose "System settings..."
6.2. Click software & update
6.3. Select all options in all selections e.g. Ubuntu Software, Other Software, Updates.
6.4.During this process, the Ubuntu will ask to input system account password for authorization, and please input your password to proceed, then click “Authenticate”.
6.5. We will need to select the server to download as below shows, usually we select Other...
6.6. Choose a Download Server , we click “Select Best Server” shown as below:
6.7. Click “Close”, it will start downloading.
6.8. If you click Detail above, it will show the downloading detail information as below:
6.9. After finishing downloading (timing depends on the LAN speed), press 3 keys “Ctrl + Alt + t ” at the same time, and type sudo apt-get upgrade -->Enter --> then input password.
6.10. Ubuntu will start upgrading, and then will ask you:
After this operation, 12.0 MB of additional disk space will be used. Do you want to continue? [Y/n], please type y and press Enter
6.11. When finished, it will show many done --> type exit to exit the dialog --> restart Ubuntu.
6.12. For the 1st time we playing the video file, it will auto pop up dialog box : Searching for multimedia plugins.
6.13. Then select all the options (e.g. Below picture: gstreamer1.0-libav / gstreamer1.0-pllugins-bad-faad / gstreamer1.0-plugins-bad-videoparsers) --> then Install.
6.14. Session-installer --> press Continue
6.15. Then we can watch anything we want from HDMI both video and sound.