In Harry Potter and the Order of Phoenix movie there's a scene where Fred and George are outside throwing something shiny and sparkly each to other in front of other students before Umbridge comes and interrupts. What was that thing?
These look like Filibuster’s Fireworks, given that the image looks more like how these fireworks were previously displayed in the films.
It’s hard to tell fireworks apart, though, so it is also possible that they are an early version of Weasleys’ Wildfire Whiz-Bangs, magical fireworks later deployed to great effect against Umbridge:
On balance, given that Umbridge was able to stop it, it seems more likely to be Filibuster’s, given her total incompetence at stopping Fred and George’s own inventions.