People have seriously suggested that Mindgeek (Pornhub) could do it. Video content delivery infrastructure is eye-wateringly expensive but Mindgeek's systems already deliver petabytes of content a day.
This was memed a lot but if they seriously get involved then I think there's a good chance that their competitor would genuinely be successful as long as they can correctly distance themselves from the pornography aspect of their business.
Edit: They also own algorithms to find and recommend videos to users, robust commenting and user interaction features on their platform, and the placement and frequency of advertising are more or less acceptable on their platform.