Amazon Echo, Google Home and other smart speakers require audio files to be able to play them back. By having every video provide URL to the Audio extracted from the video would allow playback of the audio on these smart speakers. This would allow someone to listen in what was said in the video and quickly decide on further action while sitting away from computer, while driving, etc. Simply getting an URL to the extracted audio file (encoded in mp3, vaw or any other format) would work fine.
