When to use Motion Capture

The question. When is it better to use motion capture over hand keyed animation?
-Many people are under the impression that mocap is a faster way to get animation done. - If everything goes according to plan and you use the mocap as is, without splicing together clips, then sure. But no one wants to just use the mocap as is. The actors are usually different sizes than the characters the actions will be placed on. An animator will have to go in and make adjustments to the file in order for it to look natural. In reality, most of the mocap I've cleaned has been anywhere from 50% to 85% there. That's anywhere from 15% to 50% of cleaning and retargeting.
-It looks real and it doesn't require a good animator to make sure the movement is correct. - Well, in some alternate reality, that might be the case. Here on earth, you can always tell when a good animator worked on a mocap file or a mediocre animator. In my experience, the animator behind the scenes makes or breaks the motion. An advanced animator can clean up to 10 times as much as someone just starting out. Rule of thumb, an animator can average about 10 seconds of animation a day.
-Mocap gives you the freedom to work with many different takes before settling on the final one. - Here I agree. The actor can take on a scene in any number of ways. A good director will now how to get the actor to perform well. If there is no direction on set, however, the actor will most like produce poor movements or do things incorrectly. I don't know how many times I've seen shoots where the clients came ill prepared and expected the studio holding the shoot to play the role of director. As clients, they know more about what they want then the guy sitting behind the capture station. His job is to capture the files and organize them so that it won't be a headache to go through them later.
 Its like real acting. You can't just stand there and say to the actor 'Go, do the movements'. Every time that has happened, the actor just stood there, and shrugged. There was no walk through, no direction. How would they know what to do? Knowing what is needed is key. A script, a shot list, and a goal.
-Mocap is used for every game out there, it must be easy. - Ummm, that's not true at all. Depending on the video game, some of the studios out there have preferred mocap. But not every game is made with mocap animation. Yes, its a great tool to use for characters walking or interacting in a certain way. Have you played any games lately? I really don't think that anyone has a big enough stage to capture certain leaps, dives, bounds, swinging from trees, rafters, etc. Some of that motion might be mocap, but no one can mocap a person flying. People don't fly by themselves. An animator has to go in there and make it look like we can fly. My hat goes off to them.
-Mocap seems like a pain in the a$$. Might as well just pay an animator to do it by hand. - I do love animating key poses. Its a lot of fun. But sometimes mocap is just a better solution. If you want real movement, like super realistic, mocap can be a great asset. You'll need good actors and a solid director to get the motion you want. And not to forget, a great mocap team. If you want a more cartoony look, well, you're better off staying away from mocap. Mocap really is for a more realistic look.
-"I have this great idea for a short/show/pilot. It's about this ::insert animal here:: and takes place in a ::insert scene here::. I've been thinking about maybe using mocap for the main character who is a ::insert animal here::. It would probably be easier to mocap a person, right?" - LMAO. I'm not gonna say how many times I've held back tears when someone has asked me this because of how hilarious this seems. No. You cannot ask a Human to walk around like a specific animal. No matter how many times you try to get them to move like a cat or a dog or an elephant, it just isn't happening. Yes, Andy Serkis has been a great actor, but I really don't think you realize how much of a budget comes with him and his type of service. There are very few humans who can move around like animals. Mostly because we have different skeletal structures. Maybe we can do Apes and other primates, but a horse? Are you kidding me? If I really have to explain the differences, I might just cry.

I think I got most of the obvious issues when people think of motion capture. It really is its own art form. Mocap has some great advantages. People just need to educate themselves a little more when they think about using mocap.