Russia tested the most powerful hydrogen bomb ever detonated by the human race. That footage is a 50 megaton explosion. The object that passed Earth on June 29th would have struck with 10 to 12 times that force, somewhere in the range of 50 million megatons of TNT.
That number is not theoretical. It comes from calculating the size and velocity of the object against the yield of the largest nuclear weapon humans have ever built. The June 29th pass was close enough that the question of what happens if the trajectory shifts slightly is not an idle one.