how_much_netflix.js

// how_much_netflix.js
// A script that looks through your Netflix viewing activity and
// tallys up how much time you've spent watching Netflix
//
// INSTRUCTIONS TO USE:
// Open https://www.netflix.com/WiViewingActivity and the developer console
// Copy and paste this script into the developer console and press enter
//
(function() {
  var fetchAllViewedItems = function() {
    var deferred = jQuery.Deferred();
    var viewedItems = [];
    (function fetchPage(page) {
      jQuery.getJSON('https://www.netflix.com/api/shakti/b6260b85/viewingactivity?pg=' + page).done(function(json) {
        viewedItems = viewedItems.concat(json.viewedItems);
        console.log('Fetched %s viewed items', viewedItems.length);
        if (json.viewedItems.length == json.size) {
          fetchPage(++page);
        } else {
          deferred.resolve(viewedItems);
        }
      }).fail(deferred.reject);
    })(0);
    return deferred.promise();
  };
  fetchAllViewedItems().then(function(viewedItems) {
    var totalTime = viewedItems.reduce(function(runningTotal, viewedItem) {
      return runningTotal + viewedItem.bookmark;
    }, 0);
    var days = Math.floor(totalTime / 60 / 60 / 24);
    var hours = Math.floor((totalTime / 60 / 60) % 24);
    var minutes = Math.round((totalTime / 60) % 60);
    console.log('According to your viewing history, you have cumulatively watched %i days, %i hours and %i minutes of Netflix', days, hours, minutes);
  });
})();

Updated fork here: https://gist.github.com/vineyy/6c25e8013feda5833134

The hardcoded alphanumeric part 'b6260b85' in the Netflix API changes. I don't yet know if it changes with profile and/or with location etc but it does.

There is a way to find what API can be hit to get the data. The https://www.netflix.com/WiViewingActivity page html has a JSON object defined as netflix.contextData and it has a services.data.api that tells what API can be hit. Type netflix.contextData.services.data.api on the devtool console and see yourself.

@vineyy, I saw that updated gist and @sander110419 was instructing to concatenate the build. It's here:
https://gist.github.com/eyeyen/4d3cf27a50f1c6a770cc1e683a31c89d

You can see that specific revision here:
https://gist.github.com/eyeyen/4d3cf27a50f1c6a770cc1e683a31c89d/revisions

Cheers!

I've been through all the modified scripts I can find and this is the only one that works still, Netflix change their code too much to justify any real effort in fixing the others so if you want to get this script to work, the simplest way is to open the developer console and go to the network tab, scroll down one page on the viewing history page to see what the API url should be, and correct the script.

Another thing worth noting, is that the figures it gives out are seriously inaccurate if you like to rewatch shows. Each show you watch will only appear once in that page no matter how many times you watch it.

That always changing number is build identifier for Netflix API, it probably changes with every new build of their API. You can find current one in source of the page, search for BUILD_IDENTIFIER.