if you would notice ALL mobs see the player with invisibility effect the effect does not shield the player from mob tracking or them seeing them this might not be an intended feature or it might be intended but this is known and is not a serious bug anyways
I also noticed it might be in the video that it will always spawn the same type of rabbit and the only different rabbits is the extra rabbits it spawns
The new mob added into the game in snapshot 14w25a
Yeah crashes my game too just place a log nothing else needed looks like it's all the logs
Yeah this crashed my game but i could reopen my game
this is a intended added feature to the game it was meant to be it is not a bug if you would read change logs or videos they will tell you about this
I should also mention you don't have to place it you can place a block on the bottom half of the double grass will do the same but on the previous snapshot 26c you can't place blocks on the grass also