案例：html/html5 案例     状态：可编辑再运行    进入竖版
 运行结果　
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<!DOCTYPE html>
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<html>
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<body>
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​
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<video id="video1" controls="controls">
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  <source src="/example/html5/mov_bbb.mp4" type="video/mp4">
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  <source src="/example/html5/mov_bbb.ogg" type="video/ogg">
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  Your browser does not support HTML5 video.
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</video>
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​
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<script>
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myVid=document.getElementById("video1");
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myVid.onprogress=alert("Downloading video");
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</script>
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​
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</body>
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</html>
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​