I usually watch gaming related stuff on youtube, but also the odd educational binge. Currently that's crash course (which probably isn't news to anyone), but I have a different, perhaps slightly more obscure recommendation- "Baz Battles" recounts famous historical battles, sieges and rebellions and gives some nice historical context to what's going on. Really interesting, and might even be on topic for some RP sometime!
Rhett & LInk (Good Mythical Morning), Arumba, and quill18 have to be my top three. ConflictNerd, Achievement Hunter/Rooster Teeth, Cow Chop, CaptainSparklez, Professor Stick, Mann Shorts, and Wendover Productions would round out my top ten. KnowledgeHub/AltHistoryHub and CGP Grey are up there too.