Sorry for the delay. I'm not sure why you're seeing what you are seeing. In your video, I don't see you actually posting a comment. Is that when the page initially loads or after you click the "Post Comment" blue button.
I took a video of what I see when posting a comment. The comment immediately appears as expected. I'm using Chrome on a Mac:
screencast.com/t/WOq7CiIk1
If there's any more information you can provide about how you are testing or what exactly you are seeing that would help.
Thanks,
Alex