I haven't tried any of these, but from this post it looks like some have. It is related to adding an image, but I did see one more that mentions using an <iframe> to embed video code in the same area. One of the methods talks about changing files on the server. If you do this, be sure to make a backup of the file; just in case. Also; any changes you make to the files on the server will be overwritten with each update. You would have to re-apply your code each time.

https://developers.oxwall.com/forum/topic/5145?&page=1