As an omnivore I don't really have a dog in the race so to speak, but I suspect an activist would argue that an animal that is killed without suffering is still 'murdered'. The lack of pain isn't really the point, is it?
In the same way, there are many reasons that people do things like eat 'organic' meat:
* I don't want the animal to suffer
* I don't want the animal to be 'hopped up' on antibiotics (i.e. having all their food 'laced' with antibiotics)
* I don't want the animal to be 'bio-engineered.' (i.e. farms that 'engineer' their cattle to grow to maturity very -- unnaturally -- rapidly in order to increase profits)
* I want the animal to have a 'good life.' (i.e. to spend 99% of their time from birth to death in a cage so small that they can't even turn around)
[ Unfortunately terms like 'organic' don't always mean what people think that they mean. At least in Canada (and I think the US), if an animal on an 'organic' farm gets sick and needs antibiotics, they have to go to a non-organic farm after being treated because all 'organic' livestock can't have any antibiotics in them. In general, I don't think that this is what people mean when they think about 'organic' farming practices, but sometimes it can be beneficial to humans -- e.g. someone that is allergic to any trace of common animal antibiotics in the meat that they eat. ]
See: http://en.wikipedia.org/wiki/Animal_liberation_movement
Richard Dawkins recently put up an interview he had with Peter Singer http://www.youtube.com/watch?v=GYYNY2oKVWU in 2008 about it which convinced me they are right but I still eat meat as I can't stand nearly all the vegan food I've tasted.
The reference you've provided doesn't really speak to the absolute or relative number of who hold this view. They certainly exist but I'd say they would be a small minority. Most people who cared about animals in a way that compelled them to act wouldn't see a direct 1:1 equivalence.
Interesting video.