I have installed MultiGet to my machine and I don't know how to use it. I tried to download videos from YouTube by pasting URL to MultiGet but it didn't work. So what should I do now?
MultiGet likely does not support downloading YouTube streams (tested with version 1.2.0). If you specifically want to download videos from YouTube, there are several other ways such as
ytd-gtk and many web browser extensions.
See this question for other YouTube downloading solutions: How do I download a YouTube video?