I posted a french article on my blog page, and among many comments, someone pointed out that maybe, Gilmour doesn't want the PF official website becoming a vector for Waters' political ideas.
it's just a speculation of course, no confirmation of this, but it could be a reason why Mason is allowed to post his videos and Waters not.
I know there are also legal issues with the band name (I think now owned by Gilmour and Mason ?
) etc... but it can't be the only one reason imho
I thought that after live 8 and 2011 Wall shows where David was guest, they were "friends" again.... but it seems there are still subjects that they can't find a status quo