Can someone explain this?

Editing.

I think the phone vibrating confuses the ants and they can't figure out which way to go.

I think they are worshipping their new god

Ring around the rosey...

It's fake

The phone is playing that music they always play at ice rinks

Ants sometimes do this without an iPhone too. Apart from the magnetic field being disrupted they basically rely on a follow the leader method of navigation to get around. If the leader ant gets lost and starts circling so will the rest until they eventually die of exhaustion

Heavy Metal \m/ :D

Someone is calling you

The vibration makes the bugs freak out and they don't like it so they avoid it