In google's machine learning crash course they have embedded youtube videos without scrubbers if you need to seek through the video you have to use the buttons below the video. Why are they doing this? Is there a design purpose? even the captions are shown in a different way. eg: link
closed as primarily opinion-based by maxathousand, Mike M, locationunknown, Shreyas Tripathy, Ken Mohnkern Mar 29 at 17:15
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They are doing this because they want the video to be in sync with the slideshow presentation on the main part of the page. By utilizing a single control at the bottom of the page they can more easily maintain control of your interactions as opposed to seperate slideshow and video controls. In fact, because the video is within an iFrame, any changes to the scrubber within the video cannot be detected on the main site so they would not be able to match the current presentation slide to where you seek in the video.
Another possible reason is that the video is simply too small for effective seeking, the touch area would be too hard to hit and the slightest drag would lead to large jumps in playback.