Nested closures

var movieLists = [{
    name: "Instant Queue",
    videos: [{
        "id": 70111470,
        "title": "Die Hard",
        "boxarts": [{
            width: 150,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/DieHard150.jpg"
          },
          {
            width: 200,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/DieHard200.jpg"
          }
        ],
        "url": "http://api.netflix.com/catalog/titles/movies/70111470",
        "rating": 4.0,
        "bookmark": []
      },
      {
        "id": 654356453,
        "title": "Bad Boys",
        "boxarts": [{
            width: 200,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/BadBoys200.jpg"
          },
          {
            width: 150,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/BadBoys150.jpg"
          }

        ],
        "url": "http://api.netflix.com/catalog/titles/movies/70111470",
        "rating": 5.0,
        "bookmark": [{
          id: 432534,
          time: 65876586
        }]
      }
    ]
  },
  {
    name: "New Releases",
    videos: [{
        "id": 65432445,
        "title": "The Chamber",
        "boxarts": [{
            width: 150,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/TheChamber150.jpg"
          },
          {
            width: 200,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/TheChamber200.jpg"
          }
        ],
        "url": "http://api.netflix.com/catalog/titles/movies/70111470",
        "rating": 4.0,
        "bookmark": []
      },
      {
        "id": 675465,
        "title": "Fracture",
        "boxarts": [{
            width: 200,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/Fracture200.jpg"
          },
          {
            width: 150,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/Fracture150.jpg"
          },
          {
            width: 300,
            height: 200,
            url: "http://cdn-0.nflximg.com/images/2891/Fracture300.jpg"
          }
        ],
        "url": "http://api.netflix.com/catalog/titles/movies/70111470",
        "rating": 5.0,
        "bookmark": [{
          id: 432534,
          time: 65876586
        }]
      }
    ]
  }
];

return movieLists.concatMap(function(movieList) {
  return movieList.videos.concatMap(function(video) {
    return video.boxarts.
    filter(function(boxart) {
      return boxart.width === 150 && boxart.height === 200;
    }).
    map(function(boxart) {
      return {
        id: video.id,
        title: video.title,
        boxart: boxart.url
      };
    });
  });
});