It's a rather short, little pageant that takes place in the evening on the lake outside of MK and the surrounding resorts.
Viewing can be done from nearly anywhere that has a view of the lake. Many folks like the Poly beach, the WL beach, the Contemporary beach, Narcoosee's, Fort Wilderness, etc...
What is it? Flat barges decorated with fairly elaborate lights that depict animals and other things. The lights chase, flash, change, etc.
A cute thing to see, but don't knock yourself out over it.
Ask at a surrounding resort for the times.