<button onclick="enablePreload()" type="button">启用预加载</button>
<button onclick="disablePreload()" type="button">禁用预加载</button>
<button onclick="checkPreload()" type="button">检查预加载状态</button>
<video id="video1" controls="controls">
<source src="/example/html5/mov_bbb.mp4" type="video/mp4">
<source src="/example/html5/mov_bbb.ogg" type="video/ogg">
Your browser does not support HTML5 video.
myVid=document.getElementById("video1");
function disablePreload()