Robin Good: YouTube auto-generated channels are channels that are automatically created by dedicated algorithms to collect trending and popular videos by topic.
"Auto generated channels act like user channels in that you can subscribe to them and stay updated on new videos.
In addition, auto generated channels provide:
-> The ability to subscribe and get regular updates about this topic on YouTube on your feed
-> A way to find other channels related to this topic
-> More context about this topic from Wikipedia or other sources
YouTube algorithmically determines the central topics in a video and then uses that information to develop great collections of videos for any topic of interest.
These channels do not convey any editorial opinion.
(Thanks to Alex Briscese for pointing me to this)
Via Robin Good