The YouTube channel WonderWhy is promoting vexillology with this video uploaded on November 30th, Fascinating Flag Facts. It has over 150,000 views (and over 1300 comments!).
They have done a decent job, though falling short in some aspects. For example, they repeat the often said but historically unsupported claim that the shape of Nepal’s flag refers to the peaks of the Himalayas, and the common but superficial criticism of Liberia’s county flags (which deserve some serious vexillological investigation regarding their origins and local perception).
Portland Flag Association 