Training videos have no audio when playing at more than 1x speed

Question

When watching the training videos, if I select the 2x playback speed, the video plays but there is no audio. I have tried using the Chrome and Edge browsers but the same problem occurs with both. Watching them at 1x speed is painfully slow. Any help would be appreciated.

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David Birdsall · Answer

Ron, 
 Simply put, many people, like me, don't like to hear the audio when scrubbing video. Besides, it's much more complicated and difficult for your computer/device to play audio when scrubbing video than when scrubbing audio. 
 Audio files are small single highly compressed files. These files can be streamed quickly because you just need to slice up the coded/compressed file, place each slice into a packet, and send the packets on their way. This can be done quickly with very little computing power. The same applies on the other end to decode and reassemble the file for playing. The only way to scrub an audio file is to listen to it. 
 Videos are a whole other story. Just as each broadcast television channel has two frequencies; one for audio and one for video, a video is package of a video file and an audio file. Unlike audio, video is much more complicated. (We won't get into what video so complicated.) It takes a lot more computing power to break apart coded/compressed video, package it, and stream it. Even when compressed, video streams require 100 times more bandwidth than audio. HD videos stream at approximately 5MBs. HD audio streams at 64kbs. At the other end, the video must be reassembled and decoded/uncompressed. Then the timing between audio and video must be re-synced perfectly before they can be played together properly. In order to scrub video quickly, you need to see the video. You don't need to hear the audio. Dropping the need to assemble, uncompress, and time the audio to the video while scrubbing gives the processor a little more power to assemble and play video at faster speeds. 
 Since videos are deigned to be equally playable on less powered mobile devices as they are on computers, Youtube, iTunes, Netflix, Hulu, Amazon, Sling, Crackle, Twitch, and other streaming video services don't play audio when scrubbing video in their video players.