The click layer over the embed left the bottom 22 % of the stage free. YouTube's
new embed keeps its fullscreen button 80-128 px above the iframe's bottom, so on
a stage under ~580 px (a small window, a browser zoomed to 150 %) the layer lay
over it and a click paused instead. The cutouts now have px floors (56 top, 140
bottom) and are measured against the iframe's own box.