In her first comments about an upcoming return to prime time television, Jennifer Aniston tells ET Canada that shooting the NBC hit '30 Rock,' was an absolute blast - confirming that her appearance has already been captured on film.   "It was awesome - really, really fun," Aniston said, complementing the '30 Rock' cast members, who she calls "stellar." The Emmy-award winning actress spoke to ET Canada while promoting her new film 'Management' at the Toronto Film Festival. Last week, ET brought you all-new footage of Aniston working a scene on the New York City set of "30 Rock." She joins the show for one episode this fall to play the former roommate of Tina Fey's character Liz Lemon -- who also happens to be stalking Alec Baldwin's character Jack Donaghy!