Bored with predictable reality shows, Channel 4 have come up with the ultimate gimmick - a television programme featuring a houseful of people, some of whom - the firebrand risk-takers at Channel 4 call them ˜actors' - have been told in advance what to do and say. It'll never catch on. ˜Audacious,' trills a breathless Channel 4 news release. ˜The first in an entirely new genre'. There's something eye- wateringly ironic about Channel 4 touting as brand new a show which is a hybrid of the tired, faddy, reality genre and the centuries-old phenomenon of pre-written, pre-rehearsed drama. In Bedsitcom, four men and two women come together to live in a London loft apartment, and be filmed for a fly-on-the-wall documentary. But three of the housemates are actors, with scripts and pre-planned actions - while the other three are blissfully unaware members of the public.  Executive producer Andrew O'Connor, explaining the background to the new show, said: "It was a massive undertak