I'm not buying what that dude is saying. He's making a lot of jumps and I'm not even convinced after seeing this that it does say "SEAL GANON". I dunno, the characters he's translating don't seem particularly representative of what he's showing. In fact, I've just watched the trailer again and...
We've just been discussing this in the SB. I managed to find an instance of "KWQ" which I can only conclude is nonsense.
There's also a lot of shapes and symbols that don't seem to relate to the Gerudo language, so it may well be that either the developers threw a few in there to keep us...