your darker one is preparing that stone for the eggs, i would say in the next day or so youll have many lil thugglets roaming your tank well atleast eggs with many lil thugglets in them . goodluck
Give them some time. If they've never spawned before then they're figuring it out too. from the vid it looks like all the right motions , so let them do their thing and you'll have a bunch of little monsters .