ロール間すき間寸法による選別方式。
url: https://www.youtube.com/watch?v=18xGodaLxZ4
src in: https://www.youtube-nocookie.com/embed/18xGodaLxZ4?feature=oembed&wmode=opaque
src gen: https://www.youtube-nocookie.com/embed/18xGodaLxZ4Actual comparison
url: https://www.youtube.com/watch?v=18xGodaLxZ4
src in: https://www.youtube-nocookie.com/embed/18xGodaLxZ4?wmode=opaque
src gen: https://www.youtube-nocookie.com/embed/18xGodaLxZ4