A collection of featurettes taken from the 2011 “Saga” blu-ray set.
Making the Prequel Trilogy (World building & Set Design)
https://www.youtube.com/watch?v=q6iMo35MTnA - from the Voldorac YouTube channel (1 hour, 8 mins long)
Revenge of the Sith featurette: Making the Burned Darth Vader Make-Up (not included in compilation video above).
https://www.youtube.com/watch?v=Dl6tYvzTNmg - from the MAKING OF YouTube channel (2:40 mins long)