Look what I just found! It’s the version of the early trailer for the movie Pokémon 2000 that includes this whole sequence. (I had only ever been able to find this other version before, which is shorter and doesn’t have that last bit where Misty is crying.)
What I find interesting is that unlike the other this one includes quite a lot of seemingly-final footage that actually ended up being in the movie—and yet it still has that scene. I wonder how far into the creation process of the movie they were actually planning to use it (and why they changed their minds).