YouTube unfortunately doesn't play well with linking outside sites. If you do, you can kill traffic on your channel instantly since your video would be drawing traffic off YouTube. They seem to be okay with things like Patreon and crowdfunding sites (funding to support creators and further video development) but not very much else.
Just drawing some small chunk of traffic away from YouTube isn't a really great answer anyway because you'll end up having the viewers go back immediately. It's way more important to offer better and unique content on Steemit not found anywhere else.