We don't allow autoplaying videos on your home page for a couple of reasons.
First, Google doesn't like it. Your home page speed is going to be slowed down by autoplaying videos and Google takes this into high consideration when ranking your page in search results. The slower your page load, the harder time you're going to have to get to be the number one result on Google.
Second, admit it, when you go to a website and sound starts autoplaying, it's pretty annoying. A lot of users will simply navigate away and Google knows when they do, which again will affect your page ranking.
We've spent a lot of time optimizing our themes to be as SEO friendly as possible so it's best to simply go with what works best.