可以播放本地视频文件。

<input type="file" accept="video/*"/>
<video controls autoplay></video>

通过input元素选择文件时：

1. “更改”事件被触发
2. 从FileList获取第一个File对象input.files
3. 制作指向File对象的对象URL
4. 将对象URL设置为video.src属性
5. 靠后看

(function localFileVideoPlayer() {
  'use strict'
  var URL = window.URL || window.webkitURL
  var displayMessage = function(message, isError) {
    var element = document.querySelector('#message')
    element.innerHTML = message
    element.className = isError ? 'error' : 'info'
  }
  var playSelectedFile = function(event) {
    var file = this.files[0]
    var type = file.type
    var videoNode = document.querySelector('video')
    var canPlay = videoNode.canPlayType(type)
    if (canPlay === '') canPlay = 'no'
    var message = 'Can play type "' + type + '": ' + canPlay
    var isError = canPlay === 'no'
    displayMessage(message, isError)

    if (isError) {
      return
    }

    var fileURL = URL.createObjectURL(file)
    videoNode.src = fileURL
  }
  var inputNode = document.querySelector('input')
  inputNode.addEventListener('change', playSelectedFile, false)
})()

video,
input {
  display: block;
}

input {
  width: 100%;
}

.info {
  background-color: aqua;
}

.error {
  background-color: red;
  color: white;
}

<h1>HTML5 local video file player example</h1>
<div id="message"></div>
<input type="file" accept="video/*" />
<video controls autoplay></video>