wechat-dump/wechat/static/TP_VIDEO_FILE.html

<div class="chatItem {sender_label}">
  <div class="chatItemContent">
    <span class="avatar"></span>
    <div class="cloud cloudVideo">
      <div class="cloudPannel" title="{time}" {nickname}>
        <div class="cloudBody">
            <video controls width="300">
              <source type="video/mp4" src="data:video/mp4;base64,{video_str}" />
            </video>
        </div>
      </div>
    </div>
  </div>
</div>