@nikitonsky more <video> elements _also_ take more time to process, though :)
Your initial "3 MB per video" just sounds a bit like (unintentional) fear-mongering - it's easy to misunderstand it as "the browser downloads that much more data".
And also, I just wanna ask you to consider if the tradeoff you're making here is worth it. Considering the issues I described in a neighboring thread.