Here's a list of various stuff to watch & listen to while hobbying.

Let's recommend good channels, be it any topic! Music, 40k, history, natural sciences, whatever you think is particularly good. Some quick ones:

Timaeus, who runs a series on History of Rome.

History, particularly ancient Roman & Byzantine, by Thersites

History's Empire, containing a wealth of lectures and documentaries on all manner of historical subjects. Kenneth Harl's are particularly good (e.g. to recognize voice), though the lecturers aren't attributed. It seems the channel is all about scraping together as many history videos and audios from all around, and uploading them as fast as possible, and it seems some kind of dealings with owners of some videos has at least taken place. More importantly than credit given and legalities, however, is the concentration of good stuff to watch and listen to!

Anyone has got natural science channels to recommend?

As to 40k, this video on humanity in that grimdark setting by Luetin is good. His channel is a good source for 40k material to listen to.