Just spoke with Kevin and the answer is:
Q: If you paste a link to youtube into the reply box it embeds the youtube video. I noticed that if you leave off the https:// it treats it like any other link. Is there any other way to force it to not embed the video?
A: not really unless you remove the function from the formatter as well as messing with Redactor
So unless you want to dive into the code and muck with it (make a mod) there is no way to do this.