I’m sorry to hear that. While the screencast doesn’t really cover any personal support, Discourse is offered here as a community resource.
I’m surprised that an Ubuntu box is giving you issues, since it’s used by a large number of people for hosting and is able to run node, npm, gulp, etc., without issue generally.
How do you have node/npm installed? Have you followed this post? If you’ve done anymore debugging it might be helpful to post that as well.