I think someone should make a YouTube series that covers effective altruism in a broad, accessible way, similar to existing shows in the YouTube educational content ecosystem such as SciShow.
The show would start by introducing the core concepts and main focus areas of EA (global health and development, animal welfare, and improving the future), and then dive deep into each of those areas over the course of several videos. There could also be a few videos on other causes of interest to effective altruists (such as criminal justice reform and improving science). Each video would be about 10 minutes long, and new videos could be uploaded on a monthly to weekly basis.
The purpose of the show would be to get viewers interested in effective altruism and inspire them to take action and start engaging with the EA community; indeed, the YouTube channel would be creating a new community space for effective altruists. As such, the show should respond to what viewers are interested in seeing content about rather than promoting a particular EA cause or philosophy.
There is some social validation for this idea: for example, Kelsey Piper has said that she would be excited if someone created "a YouTube for effective altruism."