Talk:Epic Rap Battles of History 58/@comment-25702233-20151215020035/@comment-5482968-20151215020240

Both screens are used to edit out behind them and replace it with a different background. However, on a green screen, other green-colored things are also edited out, so they'll use blue-screens for green objects. Blue-screens used to be the norm if memory serves before everyone switched over to green, which is far more common now.