YouTube音乐视频在iframe标签中无法正常运行的问题咨询

大家好，我最近遇到了一个问题：我用iframe嵌入了两个YouTube视频（其中一个是音乐视频），但它们没法正常运行。麻烦各位帮忙在本地机器上跑一下我这段代码，看看具体会出现什么问题，非常感谢！

这是我的代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <iframe width="560" height="315" src="https://www.youtube.com/embed/S76snYXHQcE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

    <!-- Music video -->
    <iframe width="560" height="315" src="https://www.youtube.com/embed/kffacxfA7G4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>
</body>
</html>

备注：内容来源于stack exchange，提问作者Yash porwal