I took an Acting for Animators workshop from Ed Hooks a couple of years ago, and it was a great experience. Not only was it a fun workshop, but I learned a great deal about human behavior as it pertains to acting and how to define the nuances of a character's personality and motivation through acting. Yes, observing people on your own and video taping things are good things to do, but that is only one small part of being a character animator. A lot of the time, you end up only observing the outward behavior of people without truly understanding why things happen. An acting class can help you understand the "why". By working with an acting coach, you can gain a deeper understanding of how the great actors do their thing. You can learn about how motivation and inner thought can manifest themselves in physical action.

If you are really into character animation, then I would highly recommend taking an acting class at least once or twice. It can add so much to your work in terms of really understanding how to give life to your character. If you don't want to take a class, read some books on acting. There's a pretty good book out there called "Acting for Animators" by Ed Hooks. It's a small acting book that is geared specifically towards animators (hence, the title). Good information, relatively cheap (something like $30).