These are often dubbed "Google Sniper Sites". I would NEVER recommend simply creating a one-page site. It take all of 5 minutes to add in the additional pages which will add valuable creditability to your site.
I would first determine the commercial intent / KPI of the domains. Are you selling a physical product, info product, building a list, etc. This will determine the voice / message used for the next steps.
Create your landing page: 500-1200 words, 1-3% KWD, and intelligent use of LSI keywords. H1,H2,H3 main keyword, main keyword in first and last sentences.
I would then take the same article, and create a video that is in alignment with the core concept. Your video should be no less than 3 minutes. Longer the better -- seeing how videos will drive on-site time up. Direct sales-pitches are generally a no-no, as you want to build a personal connection with your reader and walk them through the emotional buying process. IE. solve their problems and touch on fear, vanity, greed.
Last but not least, you need to add in: about, contact, privacy, terms of service pages.
You can add in some additional on-site tricks, such as hiding the action button until the video is completely done playing. Also the new craze is revealing/flashing sub-headlines three seconds after page load. This forces the readers eyes back to the headline and prevents skimming.