Just for comparison. I also bought 5 gallons of unpasteurized apple cider from Oak Glen on 10/16/2010. I too inoculated the cider with WL Cider Yeast on that same day. However, I did not treat the cider with sulfides as you did, I just let the natural bugs be.
In my inexperienced opinion and without looking at your carboy or tasting your cider, but from your description I think you are describing acetobacter. However, even by looking at the thin layer of film it's hard to tell. A flavor of vinegar is a better indicator of acetobacter.
Also, the thin layer your are describing might just be the fermentation slowly in progress. I too remember a thin layer floating around that looked like white mucus. But I'm sure it was not bad, I think it was just the fermentation slowly acting. Man, you're cider might be okay.