vue-video-player默认显示的是英文，我需要把显示改成日文。

找到这位说的，终于改对了：
https://blog.csdn.net/weixin_41643133/article/details/104828367

我的修改：
main.js:

import VideoPlayer from 'vue-video-player'
window.videojs = VideoPlayer.videojs

require('video.js/dist/lang/ja.js') // 必须引入
require('video.js/dist/video-js.css')
require('vue-video-player/src/custom-theme.css')
Vue.use(VideoPlayer)

xxxVideo.vue:

    this.playerOptions = {
      playbackRates: [0.7, 1.0, 1.5, 2.0],
      autoplay: true,
      controls: true,
      preload: 'auto',
      muted: false,
      loop: false,
      language: 'ja', // 这里写ja
      aspectRatio: '16:9',
      中略
    }