It's hard to confirm what he had videos of or who posted what, but I did see a video that talks about a character model of Joker. Might be old news.
https://www.youtube.com/watch?v=zglNi1sUmiQ
I'm inclined to believe this leak, as it makes too much sense. New FE character that promotes the next game, but different enough to not be another Marth clone. A neat Metroid character that no one expected. Joker which is already confirmed. It still leaves some leeway which reps will be square and microsoft, but they makes sense, because both of those companies have been known to be on board with it. (plus microsoft has no reps so far.)
Think about it, that person has to accurately guess Joker AND have a list that makes absolute sense. If its fake, its the absolute best thought out fake I've seen. The Nintendo reps already decided what their reps should be. The other two are probably still being decided, as they have to work with the companies in question to figure who and how that character will be implemented.