Direction, (solo) animation, and story by Eric Goldberg
Brice Mallier tagged for some of the water fx animation

Every frame of animation was painted over by a team of six watercolorists to achieve the final look. Goldberg filmed Mike Gabriel, co-director of Rescuers Down Under and Pocahontas, playing with a yo-yo to use as reference. He received a special "Yo-yo Tricks" credit in the end credits.

(Others could have maybe been involved with the FX animation, but the original post had artist unknown removed by someone who seems from other comments and edits like they were well researched)

https://www.bricemallier.com/video/Water_liquids1.mp4
http://fantasia_2000.tripod.com/carnival.htm