Did you know that scene was improvised? The director did it so he could get some real reactions out of the actors. It worked. One of the actors heart rate went so high he had to be given oxygen because he was hyperventilating. Another one had a panic attack and had to be given a sedative. Needless to say filming was ended for the rest of the day.
RIP.
The scene you posted where everybody is horrified—is real, the actors did not know they were going to be inundated with ‘blood’ so they kind of freaked out. Gotcha moment, big time!
And Hurt reprised it later, with the line: “Oh no, not again!” Hee!