http://youtube.com/vihart http://youtube.com/CrashCourse http://youtube.com/SciShow http://youtube.com/MinutePhysics http://youtube.com/PeriodicVideos http://www.youtube.com/numberphile http://www.youtube.com/sixtysymbols http://www.youtube.com/DeepSkyVideos http://youtube.com/SmarterEveryDay http://www.youtube.com/CGPGrey http://www.youtube.com/1veritasium

Plus links on my Patreon page: https://www.patreon.com/user/creators?u=2962089

Other suggestions:

Michio Kaku: The Universe in a Nutshell @ Big Think