That entirely depends on who your subscribed to. Personally all my stuff channels like Numberphile/computerphile, or SmarterEveryDay, and plenty of Blender3d tutorial channels, animators, and a whole bunch of other informative channels.

Tears of Grace has some videos that just showcase the… brokenness, seems a bit forgiving as a term, of the game.

From what it looks like to me in testing, in any given instance All is any other instance that communicates with said instance, Local is all communities within an instance, and Subscribed is just the communities within the instance you have explicitly subscribed to.