Interesting video on NOVA. Certainly this mechanism is involved in "full-tilt" empathy somehow. Funny how I immediately thought of also watching porn as am example of another situation that would use this system, which explains the addiction qualities that carries.

I haven't seen the video, you are talking about, but I am aware of the effect of mirror neurons. I think, it is important to take it into consideration when reading someone, just to know "where" the inputs come from.

I don't use mirror neurons, when I read another person. If it is someone I don't know, I use a picture to have something to "go for", but the rest of it is online readings on msn or skype, where I can have as little influence from other sources as possible, not even the tone of voice.
I guess, it can be a help to find the right information, if you can go for expressions and body language. But in terms of exercising the empathic skill, it only makes it harder. Also because the trick for me is to not interpret the impressions, and I tend to do that, if I have more than that one source of information.