and just to elaborate on that specific technique. they will often have an orca coordinate it, likely an older female. that orca spyhops to see the target prey and then signals to the other orcas when to charge the block of ice in formation. they swim fast toward the ice and then dive under right before the ice to send a wave of water over the ice. many times they will intentionally let the seal back onto the ice to be able to practice the maneuver some more. they are also wary of seal bites and prefer to tire prey out. i have even seen one instance where they don't even eat the seal in the end, which indicates they were solely teaching and/or training.
there are other techniques they use which also require high levels of communication. one of which is where they leave one orca behind who stays silent while the rest of the pod leaves the area and starts vocalizing again. (when hunting mammals, orcas stop vocalizing since mammals have good hearing and intelligence.) this relaxes the prey and makes an easy catch for the orca who stayed silently behind. once the prey is caught, the other orcas join back, and the food is shared.
i am personally of the opinion that orcas are the second most intelligent species behind humans and ahead of all other primates. there are examples of orcas interacting with dolphins, even using dolphin vocalizations. there are also examples of orcas working with humans to catch whales, where it almost seems the orcas trained the humans and not the other way around.