for sure, you don't have to pick a seed to try it. that's probably unclear. you can just go to the test spot above the crystal and it'll test that. i think what will end up doing is just not removing the possibility to test seeds even after you pick it up. if that makes sense?
That feels like adding an unnecessary step, though.
If you make it so that you can only pick one seed, and if you pick up the other, the first returns to its spot, you succeed in capturing all the functionality you want, but with one less layer of abstraction.
Especially since the videos of "how does this work" appear over top of the seed. Going near the need you want to test to see what it does, but not touching it, feels super unintuitive.
But, aside from my broader thoughts about flow, your suggestion would certainly be less confusing that the current design.