You might be interested in viewing some of the discussions of rajya sabha on youtube.
Please check the following website, http://www.clipconverter.cc/
The purpose of this web site is that you can download only the audio of the desired video discussions.
The audio quality of a sound depends on the bitrate of the sound (bitrate is a unit by which quality of an audio can be measured)
The normal audio songs that we listen has the bitrate higher than or equal to 256 kilobit per second(kbps). The 'higher quality of the sound' or 'higher bitrate', occupies more memory than a sound of 'lower quality of sound' or 'lower bitrate'.
By the use of the above mentioned website, you can download only the audio of a youtube video discussions at an audible bitrate.
If the original video of the youtube is of 200MB then by this method you can download only the audio of the video of about 15 MB.
Hope it helps
Thanks for reading.