Fix LoadProgressBar position

src/plugin.js

@@ -78,7 +78,8 @@ const offset = function(options) {
       duration: Player.prototype.duration,
       currentTime: Player.prototype.currentTime,
       bufferedPercent: Player.prototype.bufferedPercent,
-      remainingTime: Player.prototype.remainingTime
+      remainingTime: Player.prototype.remainingTime,
+      buffered: Player.prototype.buffered
     };
 
     Player.prototype.duration = function() {
@@ -116,6 +117,20 @@ const offset = function(options) {
       }
       return this.duration();
     };
+
+    Player.prototype.buffered = function() {
+      const buff = Player.__super__.buffered.call(this);
+      const ranges = [];
+
+      for (let i = 0; i < buff.length; i++) {
+        ranges[i] = [
+          Math.max(0, buff.start(i) - this._offsetStart),
+          Math.min(Math.max(0, buff.end(i) - this._offsetStart), this.duration())
+        ];
+      }
+
+      return videojs.createTimeRanges(ranges);
+    };
   }
 
   this.ready(() => {

test/plugin.test.js

@@ -38,7 +38,7 @@ QUnit.module('videojs-offset', {
 });
 
 QUnit.test('registers itself with video.js', function(assert) {
-  assert.expect(2);
+  assert.expect(5);
 
   assert.strictEqual(
     typeof Player.prototype.offset,
@@ -58,4 +58,10 @@ QUnit.test('registers itself with video.js', function(assert) {
     this.player.duration() === 290,
     'the plugin alters video duration adjusting to start|end options'
   );
+
+  const buffered = this.player.buffered();
+
+  assert.ok(buffered.length, 'buffer has length');
+  assert.ok(buffered.start, 'buffer has start');
+  assert.ok(buffered.end, 'buffer has end');
 });