The ad networks probably host their own videos. It's different when the videos can subsidize themselves through ad clicks. Here's one of Google's: https://supp

The ad networks probably host their own videos. It's different when the videos can subsidize themselves through ad clicks. Here's one of Google's: https://support.google.com/displayvideo/answer/6086451?hl=en https://support.google.com/displayvideo/answer/6086451?hl=en