Do I have to post the video on youtube? I really wanted to put my speedrun on the site, but i can't post it on youtube, is there anything i can do?

why cant you use youtube? ask the mods of the game what works for them

Post it on twitch or another video website

Google drive works quite well, if you can, do that, and keep the link to the video as public or "anyone with the link can view". Vimeo also works, but it's quite a hassle for mods to retime (as they have to download the video)