In my opinion the seek bar of a video is progress bar but its a very different problem to task progress bars. Very important is the difference that the seek bar is.. seekable. That is the computer was never waiting for the task. It's waiting on you to display the next frame at your pace and at your request. It's just assuming you want to see each frame one after the next.<br>The progress bar has two problems. One it integrates unrelated tasks it shouldn't actually do that. The computer can easily determine things like average disk speed and be able to have an accurate estimate of time remaining assuming no other tasks interrupt it. It could even tell you how much time delay there was due to other tasks interfering with it.<br>The real reason progress bars suck is because of laziness. If you actually look at widget libraries and app platforms over the past decade they really have very little to do with computing and lots to do with expression and marketing or flashiness to the user.