像播放QQ空间分享的视频，然后在拉滚动条，当看不到那视频，就会弹窗出来继续播放，滚动条回到可见位置会再回原位置-QQ space to share like playing a video, and then pull the scroll bar, when you do not see that video, it will pop out to continue playing, scroll bars visible position will return back to the or