I can't remember the name of this one. I never actually saw it, but I remember the tv promos as a kid in the late 70's. The promo always featured a scene of a camper sleeping in a mummy style sleeping bag and being attacked by some kind of monster or beast in the woods, and the down feathers flying everywhere. I think I used to know the title but I can't think of it. If I remember it was a pretty bad b-movie, but for some reason got lots of promos on tv in the 70's when it was released.
I'm betting it was Prophecy, with the mutant bear.
Andrew has a review, with video clip of that particular scene, here:
http://www.badmovies.org/movies/prophecy/
That's the one. Awesome. Andrew actually refers to it as the exploding sleeping bag scene. Thanks.