Add video to tensorboard using Visualizer

[gaopinghai]

In the Visualizer module，we can add single image to the Visualizer and then save it to tensorboard. But I do not see how to add video to the Visualizer which we can use add_video() in tensorboard writers. So I request to add this feature.

[HAOCHENYE]

Thanks for your suggestions! we may invite @hhaAndroid and @Harold-lkk to have a look should this feature be integrated.