That's not necessary, even posting images we're a bit prohibited in this forum (in a particular rank) for some instances due to graphics-heavy that affects a particular thread to fully load, then now you will try to load some videos which are much heavier? Nah..
Not only because of that. In addition, using pictures or gifs are now abused because some members here used it for trolling which is annoying (but funny sometimes) or just used it as a gateway for the sake of posting even the content is not substantial at all. What more if those shitposters are now allowed to post videos? For sure that worse things could happen.
@OP ~ I know that your intentions are nice but the consequences of your suggestion, if will be implemented, is quite disastrous.