It's obvious they shot new footage of a guy in a Vader suit and inserted him into the castle background. I can tell because the guy doesn't look anything like Prowse.

Well you are right, you aaarrrreeee right. That's one of the rare, Sebastian Shaw in helmet shots! Prowse was on Green Cross Duty, so they tried the other DV suit actors, below is Bob Anderson on the 'leave' location:

...think they tried to blame the photographer for that one.

And James Earl Jones failed because he couldn't go two seconds with out a puff.

My hearing isn't what it used to be but wasn't Pacino deleted from the Jedi Archive?

Maybe from the Jedi Archives but not from Jedi4chan