This is actually exactly what I want to get freelance work doing as I build up my portfolio of shorts and other video projects. I stumbled across some pretty broad and in-depth tutorials by a Youtuber named Mt. Mograph, who has almost 80 videos regarding a multitude of Motion-Graphics concepts, tips, tricks, and ideas. All of these videos he has named "Summits," 1 through 79 so far.
https://www.youtube.com/watch?v=Mtv8QptWNbg
My plan is to begin going through all of these "Summits beginning in June, and work through all that they teach in order to begin producing my own original motion-graphics professionally and efficiently. One of the biggest aspects about motion graphics that makes it rather fun, and easier than you think, is that most of the 2D motion-graphics are created by duplicating, echoing, repeating, tiling, and kaleidoscoping any number of simple polygonal and shaped-based animations. Which means that with little work and a few layered effects, you can get a result that looks like it took you hours if not days to make, which is what creates visual splendor and perceived value.
I'm not entirely sure what a Videography job looking for Motion-Graphics skills would be looking for exactly. My best guess is that they may want you to be capable of creating Lower-Thirds animations for interview or new-cast styled productions, as well as basic Logo reveals and transitions, other overlay animations to place video content within, and perhaps something like those music videos where texts of different sizes appear as the lyrics are sung. But that's about all I think would be the most necessary. Anything beyond that is getting into the more conceptual and creative stuff used for commercial advertising and television bumpers, which is usually done by far more experienced and specializing motion-graphics artists. Although I'm fully prepared to go in that direction despite not going to college for it. I'm already pretty experienced doing visual effects with AE, in so far as I've gotten some extremely favorable results. But I want to expand my experience and built my portfolio in order to do the more elaborate and detailed motion-graphics not only for my own work, but also to hopefully get some serious work creating both simple and complex pieces for other producers and content creators.