Rotoscoping was a technique Disney animators often used to recycle footage from older animated films. They would draw over existing animation cells to make new scenes with characters with similar designs, characteristics, and movements. As you can imagine this will save huge amount of time and money for the studio.
Movies featured in these videos below are: Sleeping Beauty, Beauty and the Beast; Snow White and the Seven Dwarfs; Robin Hood and The AristoCats; Bambi; Alice in Wonderland; The Fox and the Hound; The Sword in the Stone; 101 Dalmatians; Cinderella; The AristoCats; Pinocchio; The Jungle Book; The Many Adventures of Winnie the Pooh. Enjoy!