WordPress Speed Up Service | WordPress Website Maintenance Packages Reply To: A way to change video SRC priority and order? Want to list WebM first, then MP4, by Ah-HAH. It was the fact I had two ancient media-playing plugins still activated (as I’m sure you could immediately see there in the HTML output code). This is a 10 year old blog after all; I’ve got so much detritus on it that as I was writing my previous comment, I thought to myself…”hmmm, there’s a lot of stuff in that <video> tag there…perhaps some of that extra junk is getting in the way” I’m no programmer but I am an I.T. consultant and trial and error is what we do…deactivating those two plugins did the trick, combined with your nice little functions.php modification. Thank you so much, Jacob! Reply To: A way to change video SRC priority and order? Want to list WebM first, then MP4