It is possible to drive traffic from a banner in a YouTube clip to a website, as long as one can prove to YouTube the ownership of the site. There are several ways to do that as explained here. Since we have no way to prove ownership on a Canvas course, we can't establish a direct link for visitors to click on the promo and get to the course. I believe it shouldn't be a big deal for the dev team to to learn Google / YouTube requirements and come up with a user friendly solution.
Sometimes you would want to put a short promo clip on YouTube to attract visitors to your course. one scenario may be attracting potential students to consider your institution. YouTube now has a feature that lets you point to your website. They applied a mechanism to verify your ownership of the redirected site. So in order to have a direct link to a Canvas course, we may need the dev team to develop an solution that will align with one of the options Google / YouTube provide.