As has been explained below, four members of the LEGO community on Flickr, namely Ethan, Joe, LASW and JJEffects66, have attempted to get Legoboy12345678's main channel taken off you tube by putting copyright claims on his latest video, a remixed trailer for his next Brickfilm, Landings on Nadiem. Luckily for his many fans, and indeed David himself, his channel will remain active.
JJEffects (John) seemed to blackmail Legoboy on Flickr, and previously blackmailed Ghartso on you tube by making him doing most of his film for him. This led to a huge "war" on you tube between the two, ending with Ghartso hacking into John's account and terminating it. Although Ghartso eventually apologised to John with a video, this just shows how the war went too far. There were arguments and it ended in the deletion of an account. John seems to have started a secret account, which his haters are trying to find.
As for what happened to David, trying to shut down such a distinguished Youtuber with so many subscribers is even worse and heaps even more chame onto John. Yes, Legoboy has annoyed many by seemingly copying others' designs, but to try and shut down his account it terrible. Actions and wars such as these could end up destroying parts of the LEGO community if they aren't nipped in the bud. Better than that, they shouldn't happen in the first place. Hopefully the situation will calm down and everything will go back to normal.