Streaming video and audio uses a lot of bandwidth but there are many occasions when the video part is superfluous. eg. I was watching the following lecture on YouTube:
https://www.youtube.com/watch?v=LNHBMFCzznE
And although it's useful to be able to see the lecturer it's by no means essential. It seems the Chrome browser has an extension which permits you to stream just the audio and thus save a stack of bandwidth:
For Firefox use Youtube Audio by Animesh Kundu to do the same.
If you wish to download and record the audio use YouTube Video and Audio Downloader (WebEx) by RayLo. This however entails downloading the full video and then striping the audio from it.
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
Wondershare All my tube, allows you to download just audio as an MP3. not a freeby but you can download from any video site. Downloading as an mp3 uses less data than watching the video.
If you're after audio only I subscribe to dozens of Podcasts and audio books for free. Recently discovered Old Time Radio plays, they're around the web and in bunches of MP3, millions of them, again all public domain copyright free. I use 4K Video downloader for YouTube which has a setting to only download MP3 soundtracks off videos.. In all I have about 300 years of audio plays and books.. lol