I’m going to add a couple other recommendations. First, the part of this talk that begins around the 2 minute mark, which is great general advice.
The other tip I’d add is since your talk is so short, use it to introduce people to the argument in two to three books that you found most persuasive. The idea would be to get them to conclude “that book sounds interesting, I should check it out.” For example, you might choose Rollback, Ron Paul’s “Revolution,” and Rothbard’s “The Ethics of Liberty” as books to touch on and make sound compelling enough for normal people to check out, without sounding so alien they dismiss them as crankish before they check it out (the biggest obstacle to the liberty movement is that its enemies, having control over the education-information system, has people well-trained to dismiss out of hand certain names/people/ideas without even looking into them. Trust me, I know. Some time maybe I’ll tell the story of how long it took before I started examining Rothbardian ideas for myself, and why).