Erm ,what about the videos where people have been beheaded? I have not and will not ever watch one, but its not some tidy guillotine. What about Lee Rigby, the soldier in England who was run over, then hacked to death in a London street? The murderers who did that certainly would have no problem with killing people in cruel ways, especially if they were given state sanction.

For other morbid Medieval executions, read about being broken on the wheel. It's hideous.