More info here: http://www.mattevanoff.com/2015/03/new-netflix-autoplay-bookmarklet/
Basically Autoplay-Bookmarklet.bookmarklet.js is the main bookmarklet. Click it when you are watching a TV show on Netflix to get rid of that thing that comes up that asks if you are still watching.
Raw Bookmarklet: javascript:(function(undefined){if(window._ME&&window._ME.autoplayer){window._ME.autoplayer.playTime=window.prompt('Autoplay already started! Updating playtime. \n How many more minutes would you like to play for?')601000;if(isNaN(window._ME.autoplayer.playTime)){window.alert('That's not a number jackass.')}window._ME.autoplayer.startTime=new Date();return}window._ME={autoplayer:{}};window._ME.autoplayer.playTime=window.prompt('How many minutes would you like to play for?')601000;if(isNaN(window._ME.autoplayer.playTime)){window.alert('That's not a number jackass.')}window._ME.autoplayer.startTime=new Date();var lastUpdate=new Date();window._ME.autoplayer.interval=setInterval(function(){var currentTime=new Date();if(document.getElementsByClassName('player-autoplay-interrupter').length>0&&document.getElementsByClassName('continue-playing').length>0){document.getElementsByClassName('continue-playing')[0].click()}if(document.getElementsByClassName('player-postplay-autoplay-header')&&document.getElementsByTagName('video').length===0&&document.getElementsByClassName('player-postplay-still-hover').length>0){document.getElementsByClassName('player-postplay-still-hover')[0].click()}if(window._ME.autoplayer.playTime&¤tTime-window._ME.autoplayer.startTime>window._ME.autoplayer.playTime&&document.getElementsByClassName('player-play-pause').length>0){document.getElementsByClassName('player-play-pause')[0].click();clearInterval(window._ME.autoplayer.interval);delete(window._ME)}lastUpdate=currentTime},1000)})();
This one will restart the "sleep timer": javascript:(function(){window._ME.autoplayer.startTime=new Date()})();
This one will disable the whole thing (clicking refresh on the page would basically have the same result): javascript:(function(){clearInterval(window._ME.autoplayer.interval);delete(window._ME)})();