Adding WebM video without transcoding?

I have 2 video’s on my homepage.
I created 2 WebM videos: One that is 340kb and one that is 512kb. When I upload them to the Media Manager, it transcodes them to MP4’s with a size of (respectively) 973kb and 3,7MB! This makes a huge difference in load-time since the large video is above the fold…

Is there a way to place the small WebM video without transcoding? (No external solution, because I’m using the large video as a background video inside a VideoBox, so a VideoPlayer is nog good)

Thank you for your reply.