视频video组件播放视频 videoContext.play() 无效？

openVideo() {
      this.isPlay = true
      setTimeout(() => {
        let videoContext = wx.createVideoContext('myVideo')
        videoContext.play()
      }, 200)
    },

<video v-if="isPlay" id="myVideo"
                :src="video_url"
                :show-center-play-btn=false
                :controls=false
            >
            </video>
            <div class="video-back" @click="openVideo()" v-show="!isPlay">
                <img src="../../../static/image/play.svg">
            </div>
            
            
                

  在模拟器和真机上均无法播放。 videoContext.play()无效。