I have no experience with the inner workings of SMF, but one would think that by 2017, the ability to automatically recognize photo and video links as such without having to insert code would be pretty standard. I manage a blog that utilizes Wordpress, and very seldom do I ever have to do any coding. Posting and/or linking images and videos is very simple. For links, it's literally just copy and paste.
Wordpress and Simple Machines Forums exist for different purposes, but at their heart, they do similar things. One makes those things incredibly simple while the other doesn't, and that 'other' is the one with "simple" in its name.
With that being said, how long has it been since the SMF backbone of the site was last updated? Perhaps this issue has been addressed and is just an update away, although part of me kind of doubts it.