In my experience, video content - or still images or audio for that matter - does not register as a duplicate to text content. I'm doing something that is parallel to what you describe and have had nothing but good results.
So long as the text content still exists on your pages, I don't see how embedding a video version of the same content would hurt. If anything the I would expect the rich content to help, especially from a user perspective. Should reduce over all bounce rates and increase time on site.