How this is so small.
The music loops after only 3.6 seconds. Compressed at 48 kilobits / second, this would've been 21.6 KB, about half of the movie. It could've been compressed more or less, but it still leaves enough room for the rest of the movie.
The eyeball is a movie clip that's reused in multiple places, ie. the flower, the bald man, and the background at the end. The petals probably also reuse the same symbol as well.
The colourful bombs are the same movie clip, only with different tint values added on top. The original was most likely white.
A whole ton of tweens.
Hope that explains it enough.