Wow. I typed the first reply here, but deleted it as I thought I was being controversial. It did however include comment on the recent Nat Geo edition on science deniers, mild by comparison to the good natured comments that did eventually follow though.
While I am a meat eater myself, I could happily be an ethical vegetarian - as my children all are - if not merely because of the question, 'Could I kill and butcher the meat I eat myself?'. Clearly in my case, the answer is 'no'. Fish perhaps...
In a similar vein (I kid), could I waste film if I had to cut the hoofs off animals? No, again. There lays the conundrum; is doing, using, or eating something OK if all the nasty business happens elsewhere by someone else? I assume animals are not farmed just to make film though, and film's use of animal by-products is one of convenience? Like alternate fuel sources for cars, unless it is uneconomical to use something, and alternative rarely surfaces.
What I can say for near certainty though, is the financial impetus to develop an alternative for film will almost certainly never exist...
By the way, in the extracts field, I am already there - as I am not able to eat Marmite, confining myself to the more ethical. better tasting, better for you, Vegemite. Skj.