Listing down the youtube channels that I am currently subscribed to.
Studio C: They make 4-5 min sketches to make us laugh.
Movieclips Trailers: For all the newly released trailers.
T-Series: Bollywood songs.
Saturday Night Live: Comedy sketches featuring famous celebrities.
YFilms: Indian Mini-series.
TheViralFeverVideos: The best Indian Mini-series makers. Better than YFilms.
Kenny Sebastian: Indian Stand-up comedian. Part of the Bangalore based The Improv team.</li>
Disturb Reality: Videos which teaches Magic stuff.</li>
Charlie Rose: The quality and content of the interviews he takes is amazing. Serious kind. His talk shows are no joke.
TheEllenShow: The best of the comedy celebrity talk shows. No politics. No bullshit. Just entertainment.
The Tonight Show Starring Jimmy Fallon: Love it for the celebrity talk show and the games.
Late Night with Seth Meyers: Very good celebrity talk show.
LastWeekTonight: Takes on politics and current affairs topics with comdey. Takes on issues far better than the occational digs of Jimmy Fallon, Steven Colbert and Seth Meyers.
The Late Late Show with James Corden: Carpool videos are amazing. Brought some variety to the table.
The Late Show with Stephen Colbert: Not the best in the lot, but definetly worth watching most of the times.</li>
Most people would know these companies. All are Technology based companies, as I am more inclined to the same field.
MIT OpenCourseWare: Contains MOOCs and talks from the Massachusetts Institute of Technology (MIT). You can find large content of video materials from their OpenCourseWare initiative. Makes this the best of the lot.
nptelhrd: Not specifically a single University channel. Contains lectures from the NPTEL initiative by the IISc/IITs. Large content base. Most of the topics are science and technology based.
UCBerkeley: Contains MOOCs from University of California, Berkeley.
caltech: Contains Seminars, talks and lectures from California Institute of Technology (Caltech)
stanfordonline: Contains Seminars and lectures from Stanford University
YaleCourses: Contains mostly lectures from Yale University. Range of topics includes science, history and politics etc.
TED: I don't need to explain much about TED and what they stand for I guess. Most of the times they bring out amazing lectures with occational flops.
TEDx Talks: The less impressive version of the above. There are amazing videos even more awesome that the original TED ones. But because of too many videos, finding excellent talks are not that easy.
TED-Ed: Amazing animated educational videos and puzzles.
Seeker Daily: Producing quality short videos about current affairs. Good place for learning more about global issues through short videos.
National Geographic: Youtube handle of the National Geographic. You may not find full length documentaries here. I personally watch alot on WW1, WW2 and the Cold War.
thenewboston: Excellent channel for Programming, Web design etc.
Khan Academy: Youtube handle of the famous Khan Academy. A lot of basic math, physics, chemistry videos. Good to refresh your memory.
Big Think: Amazing channel with very good educational content, sometimes delivered by experts.
TechCrunch: Brings out news about new start-ups and new internet products.
CNET: Latest tech news and reviews about new products.
sentdex: I love his Python tutorials on Machine learning, NLP etc.
Nick Feamster: Princeton University professor. Personal choice as he produces videos about Computer Networks, SDN principles etc.
The School of Life: Deals mostly with emotional education.
It's Ok To Be Smart: Channel for science from atoms to universe.
MinuteEarth: Science and stories about our awesome planet.
BrainCraft: Channel dedicated to psychology and answering why we act the way we do.
Physics Girl: MIT graduate makes videos on Physics.
The Science Channel: Videos related to Space Science (not that active now)
Vi Hart: Interesting real world math videos.
The Royal Institution: Videos about science. The Royal Institution is a 200 year old independent charity based in London dedicated to connecting people with the world of science through events, education etc.
I will keep updating this list if I add anything more.