Diagetic and non diegetic sound

                                                         
Non diegetic sound is

Sound whose source is neither visible on the screen nor has been implied to be present in the action:
an example of non diegetic sound

• narrators commentary
•  sound effects which is added for the dramatic effect 
•  mood music

Diagetic is Sound whose source is visible on the screen or whose source is implied to be present by the action of the film,
examples of diegetic sound:

• voices of characters
• sounds made by objects in the story
• music represented as coming from instruments in the story 
  
  In the first 30 seconds of this film it uses non diegtic sound 
  
  https://www.youtube.com/watch?v=H63f7g7ETRI
  
  Diagetic sound is in this film in 2:10 (talking)
  
  https://www.youtube.com/watch?v=0DM8o0IOIR4

Green screen research

These films use a lot of green-screen production to emphasis the special effects.for example could be falling of a cliff, or jumping( super-jump). The grey mostly uses green screens when showing the snowy, mountain backgrounds. The avengers uses green screens when showing battle and buildings blowing up in the background when they are battling. Furthermore Iron man uses green screen when he is flying and buildings on fire etc.