The Download Now link directs you to the Apple iTunes Store, where you can continue the download process. You must have an active iTunes account to download the application. This download may not be available in some countries.
From Stefan VD:
Turn Off the Lights browser extension dims everything in the background, so you can enjoy the video you're watching without any distractions. Is now available for iPhone and iPad. This app is the darkest mobile web browser, where it loads pages super fast. With the power of the Apple WebKit rendering engine. Optimized for Facebook, YouTube, Twitter, Yahoo and Google. No white screen anymore when browse the web on your mobile device. With one tap on the white lamp button, it dims the web page. And if there is example a YouTube video on that page, it will highlight automatically this video player.
These days you see more and more students, teachers and also working people with their phone in their hands. And at night you see all that light is shining in their eyes. Thanks to Turn Off the Lights is this problem solved, because with one tap on the white lamp button it add a black transparent layer on top of this website.