"You should be comfortable using Github, having basic programming proficiency in at least one language and have a reasonable grasp of HTML and Javascript. Experience collaborating via IRC is handy, but not critical."
Basic proficiency in a random programming language and some grasp of HTML is something that's taught in a high school computer class or any introductory course for a tangentially related college program such as statistics or physics - this level of proficiency is something that a random student (of not-computer subjects) is somewhat likely to have.
I mean, it definitely is technical and does require some background, but it's appropriate to say "a bit technical, but you don't need to be an expert".
They may not teach HTML, but my alma mater taught python to freshman physics students. By senior year, you would have at least learned two additional languages. That's just from the physics courses - if you decided to take an intro to cs course (which most did), you would have learned a fourth (but probably not a FORTH).
While they wouldn't specifically know HTML or Javascript, they'd know enough to how to read the language documentation and gain basic proficiency in a week. They wouldn't be a Douglas Crockford, but they could help out an open source project.
Of course, this was at a state school. Things might be different elsewhere.
Not very. Watch the two videos and you should be able to complete the tasks without a problem. Only snag that you may run into the common error where the first form HTTP and the second form is HTTPS, but the workaround is listed in the instructions (complete each form individually, merge results manually).
So... very technical?