Vin Diesel is well known for sharing set videos and photos from his films on his Facebook page. His latest live video post featured a surprise guest - James Gunn, director of Guardians of the Galaxy vol. 2 in which Diesel plays the part of Groot. When the video he starts he appears to be in utter shock and almost speechless - until a wild James Gunn appears out of nowhere and tells us that Diesel is the first cast member to see footage from Guardians of the Galaxy vol.