The best solution I've seen is what Temple Grandin recommends in regards to independent 3rd party observation and review of meat harvesting/processing facilities (that would not be a radical activist 3rd party observer). It seems that handling is improved immensely when workers are actually held accountable because "big brother" is watching them 24/7. Just being aware that there is some level of supervision helps. I mean you don't *always* get the most top notch workers in a slaughterhouse, people aren't exactly lining up for that lovely job. That is not to say that there are not fantastic workers in the industry, I know some really great meat cutters that take pride in their work. 

Now in the facilities, for example, where the mob is substituting horse meat for beef, you could certainly expect more problems overall. Things can only get better if upper management is going to follow through with the whole program. There are going to be facilities where they don't want to make the investment to improve the operating procedures, even though it seems it would certainly pay off in the long run. I think you will find that in every industry, human nature that some will be greedy, or lazy, or just not care one way or another. 

I don't know that they can do anything about undercover videos in the US in regards to freedom of speech. Darn near everybody has a camera on their cell phone these days, you really need to think about what you do because anyone could be recording you just about anywhere in public or the work place. The lack of privacy anymore is a little scary actually. 

If disturbing videos are coming out of private facilities with rules about photographing or filming then those should be sent to the governing agencies who will hopefully respond. It is usually when the governing agencies fail to respond that these things go public, and that is also sad because the governing agencies are in place to theoretically address those issues. 

"It's really quite amazing what a horse will do for you, if he only understands what you want. 
And it it's also quite amazing what a horse will do to you if he doesn't." ~ Bill Dorrance