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 original location