How to disable seeking with HTML5 video tag ?

Extending the answer from @svetlin-mladenov, you can do the following to prevent the user from seeking any part of the video which has not been watched yet. This will also allow the user to rewind and the seek out any part of the video which had already watched previously.

var timeTracking = {
                    watchedTime: 0,
                    currentTime: 0
                };
                var lastUpdated = 'currentTime';

                video.addEventListener('timeupdate', function () {
                    if (!video.seeking) {
                        if (video.currentTime > timeTracking.watchedTime) {
                            timeTracking.watchedTime = video.currentTime;
                            lastUpdated = 'watchedTime';
                        }
                        //tracking time updated  after user rewinds
                        else {
                            timeTracking.currentTime = video.currentTime;
                            lastUpdated = 'currentTime';
                        }
                    }


                });
                // prevent user from seeking
                video.addEventListener('seeking', function () {
                    // guard against infinite recursion:
                    // user seeks, seeking is fired, currentTime is modified, seeking is fired, current time is modified, ....
                    var delta = video.currentTime - timeTracking.watchedTime;
                    if (delta > 0) {
                        video.pause();
                        //play back from where the user started seeking after rewind or without rewind
                        video.currentTime = timeTracking[lastUpdated];
                        video.play();
                    }
                });

The question is quite old but still relevant so here is my solution:

var video = document.getElementById('video');
var supposedCurrentTime = 0;
video.addEventListener('timeupdate', function() {
  if (!video.seeking) {
        supposedCurrentTime = video.currentTime;
  }
});
// prevent user from seeking
video.addEventListener('seeking', function() {
  // guard agains infinite recursion:
  // user seeks, seeking is fired, currentTime is modified, seeking is fired, current time is modified, ....
  var delta = video.currentTime - supposedCurrentTime;
  if (Math.abs(delta) > 0.01) {
    console.log("Seeking is disabled");
    video.currentTime = supposedCurrentTime;
  }
});
// delete the following event handler if rewind is not required
video.addEventListener('ended', function() {
  // reset state in order to allow for rewind
    supposedCurrentTime = 0;
});

JsFiddle

It is player agnostic, works even when the default controls are shown and cannot be circumvented even by typing code in the console.