I thought it was okay. Bulk tanked the hit of Zap Cannon and then got ready as Jolt was erupting from the ground and fired off a Stored Power, which fires into the air and back down again. Jolteon is close enough to get hit by Counter. Counter is usually used as a move to attack a Pokemon who is close enough to get hit.
Normally, I would use Counter as a way to use the Pokemon's momentum against them, whether they be using a special or physical move, just as long as they are close enough, they can take advantage of their attack or attack stance and smash them. Mirror Coat is something to bounce back Zap Cannon and Stored Power, but he didn't specify he was bouncing the attack back, just making quick work of Jolt by hitting him as Jolt was going to hit him with Stored Power.
Literally, many of these moves can be used in different ways. Thunderbolt can shock a body part and you can use it as Thunder Punch or Thunder Fang or even an electrified tail. Because Counter is open-minded in this way, anybody who gets close and tries to attack, no matter what attack it is, just as long as the Pokemon using Counter is close enough and hitting an opponent who is attacking them up close, then that's good.