I go to the video on Youtube, click on share, go to the embed option, cut and then in the Squarespace editing screen paste it into embed code (gear icon), then save. Maybe the Squarespace theme I have does not support that? I also tried just copying the code above and pasting it into the embed code window. The video works, just not automated. The link above autoplays for me when I go to it directly outside of Squarespace.