Ah, good thought. Thanks, I’ll repost over there.
I am having the exact same issue, which is very frustrating. Did you come across a solution yet?
I’ve tried the same as you did, and also tried various plugins such as Advanced Responsive Video Embedder, Video.js – HTML5 Video Player for WordPress, and Viper’s Video Quicktags. Additionally, I’ve tried disabling every plugin to see if there was a conflict, but it still doesn’t work.
One thing I’ve noticed is that, when I have my code specifying the video display size… when I’m editing the page and switch from the Text mode to the Visual mode, the video previews at my specified size, but the published page always defaults back to fill the entire browser width. So I’m guessing there is some sort of conflict where another file is overriding our code, but have no idea where or how to track it down.
Anyone? 🙂