video标签在ios设备上，视频播放 会脱离文档。
webkit-playsinline和playsinline: 视频播放时局域播放，不脱离文档流 。但是这个属性比较特别， 需要嵌入网页的APP比如WeChat中UIwebview 的allowsInlineMediaPlayback = YES webview.allowsInlineMediaPlayback = YES，才能生效。换句话说，如果APP不设置，你页面中加了这标签也无效。
如果以上设置都未生效，可以使用iphone-inline-video-master这本版本库，只需要引入一个js即可。(Video Tags on the IOS device, video playback will be separated from the document.
Webkit-playsinline and playsinline: play local playback without leaving the document stream. However, this property is quite special and needs to be embedded in the page APP such as the WEChat UI WebView allowsInlineMediaPlayback = YES webview. AllowsInlineMediaPlayback = YES to take effect. In other words, if APP is not set, the label added to your page is invalid.
If none of the above settings are valid, you can use the iphone-inline-video-master version library, just by introducing a js.)