Another very cool YouTube channel to add to your list of YouTube channels is CGP Grey.
This is not a channel devoted entirely to science as there are quite a few videos released discussing history and current events, but it is a very informative channel that will definitely increase your knowledge. For example, two recent videos focused on the electoral college in United States politics. These videos discussed the history of the electoral college, what it was designed to do, how it's not doing what it was designed to do, and the role it played in the recent November 2016 elections.
Recent science videos include animal domestication, transporters, and solutions to traffic jams. Despite it not being entirely devoted to science, the channel is devoted to informing people on various topics and I look forward to new videos. On average videos are released about once a month, although that has increased a bit with the electoral college videos coming out right after the election.
So check it out. I think you'll like it!