Thank you very much for your answer. This is a good workaround.... but it doesn't work for us as we have the multimedia plugins filter disabled on our VLE. This is because we want to have full control of what displays as a link and what is embedded. I could enable the filter just for the quiz page of course.
Still, I would prefer to be able to embed the video as an iframe as with the iframe we have full control of how the video is embedded (eg size).