“This video is sponsored by SquareSpace”
– Many YouTubers, apparently
SquareSpace was released in 2004 with an emphasis on ease-of-use, polished templates, and an experience aimed at quick and easy to learn website building.
About
SquareSpace is renowned for their focus on visual design and automatic handling of hosting,security, and software updates, as well as a rich set of features built-in, mitigating the need for plug-ins.