I hope this is never allowed. It is extremely annoying if you are looking at the boards on a mobile, or in a public place.
Question! If I were going to view the uploaded video in the forum, will it redirect to another tab or website?
Of course it is as this website tend to redirect you from that thumbnail to that specific website, actually it's not uploaded instead a link. I agree that this forum shall never implement videos in threads besides this is a forum not a social media site.