经过不懈努力，终于调试成功，正确播放代码如下：
<video src="{eyou:field aid='$field.aid' addfields='video_mp4' /}" loop="loop" controls="true"
width="100%" height="490">
{eyou:videoplay aid="$eyou.field.aid" autoplay="off" id="video"}
<source src="{$eyou.field.video_mp4}" type="video/mp4"/>
{$video.hidden}
{/eyou:videoplay}
</video>