That's THE cause of the whole problem! It is against all BBFC rules to show someone putting aerosols in a microwave, because it can easily be imitated by anyone, with disasterous consequences.
It wouldn't only be little kiRAB who'd copy, I bet many teenagers would want to experiment, because it is so easy to do, but not many people think about it.
Because of the cut, the film doesn't sync up to the commentary, and WB won't pause the edit, so they've removed it.