I'm pretty sure a friend of mine is responsible for those flyers. They're part of an animator's collective and I assume were/are planning on animating the voicemails.
That's a pretty long video! I haven't asked her about this so I might be wrong, but it was about three years ago that she was working on something similar. I could definitely be wrong!
I'm surprised this isn't more well known, I thought it was relatively known, I posted this link in another comment, but here's a great video about this: