What is this new hack?

[TimKwink]

I play a lot of eggwars and lately i came across some hackers using a hack i have never seen before.
They place a block and then fly too the next island. I try to record all of them but a lot of times they stop when i start recording...

 

[ISTY.]

They place a block down, because you need to place a few blocks for the fly to work, so they don't get it's not a "new hack",

 

[Mighty_Pig]

It is a fly hack. I think the fly hack use a bug in Minecraft.