"Animators are encouraged to do as much planning as possible before they start a shot. Indeed, planning ahead and putting effort into the beginning of a shot is the best way to ensure a smooth ending. So why is video reference so dangerous?"
Video reference can be your best friend. With realistic animation, high action or physical performance, and certainly animals and creatures, you are smart to gather as much reference as you can. As an animator you will be required to produce believable representations of far more actions than you could possibly have personal experience performing. That is to say, I doubt there's a person that lift an 80lb chaingun over their head in triumph, who can also do a perfect pirouette! If you can find that person for me, I'd love to meet them! We all have our strengths and weaknesses, so video reference can really be a great tool during planning.
When it becomes tricky is if you are doing a shot that has ANY departure from realism. The instant you start embellishing and exaggerating to create more appeal, you are diverging from the video reference. By definition then, video reference becomes something that by comparison is a poor representation of the amazing appeal that we have in our heads. We can create insane poses, ingenious timing, inspiring silhouettes, all from our imagination. When you start using video reference however, the message can get muddied. What do you do?
With cartoony shots, the point is to make sure you are drawing from a single aspect of the video reference at time. Borrow a pose here, an interesting timing there, a great composition there. Do not, under any circumstances, copy the reference expecting to improve upon the motion drastically afterwards. This is the perfect way to get a very weak foundation that will not support the great workflow you've been working so hard to perfect. The animation just won't ever depart from the reference enough to make something really appealing.
Remember, video reference is not just a good idea, it is essential. When working with very realistic motion or animals, you need to have a wealth of reference to draw from. However, the moment you start wandering into the realm of pushed realism, cartoony, or exaggerated movement, you have to pick and choose what you will use from your video. Don't copy frame by frame but rather wait until a certain single aspect of the video inspires you. Stick to your workflow to build a strong foundation, and the inspiration from the reference will help your shot shine instead of dulling it down as you move forward.
Kenny Roy is an animator, Owner of Arconyx Animation Studios, animation author and mentor at KENNYROY.COM. He has worked on King Kong, Garfield and Scooby Doo 2: Monsters Unleashed.