Actually it is an update version of the video that support supplied. Instead of uploading an outdated page that looks tacky, you are creating a new one with copying and pasting from the sales page. But, unless you have some knowledge on how to create pages and use Elementor it can be tricky.
As for the video they supplied, it is simple and easy to follow and can be use today. It helps to have some knowledge of how websites work though.
Personally I am going to take both methods and combined them and make unique pages so they are not like anyone else.
As for niche websites, it really depends on the platform (html or wordpress) on how to upload them. The best thing you could do is Google it and look at the video section. Chances are someone has already asked the question, so there are bound to be many videos out there to help. You just have to look for them.