Manjaro uses a rolling release model, so videos are not the most up-to-date resource for installing things, especially Ubuntu videos! 
Therefore read this:
(At a minimum The N00b guide to installing software, but the other sections could be useful to you as well if you don’t know much about them)
Then reverse the steps you already took from the video and install your chosen software the right way!
P.S. For the future, please use this methodology to post links / pictures / videos
P.P.S. If you can’t find “Manjaro” instructions, follow “Arch” instructions and if you can’t find anything, please post a question here!