Some rare footage from the shooting of the original trilogy has surfaced on YouTube featuring bloopers by the cast! The footage was gathered by J.W. Rinzler, an editor who found the footage in an archive. A small group of people was selected to see the footage at San Diego ComicCon, and after a wait, some of the footage is now able to be viewed by everyone. The video is included after the article.
Also surfacing in the past few days was a Laserdisc containing 30 minutes of raw behind-the-scenes footage of the filming of Return of the Jedi. The disc recently sold for $699 on ebay, and the winner plans on making footage available in digital format for everyone.
Note: The video is silent the first 48 seconds. This is working as intended.
Buzzfeed has also already made gifs of some of the footage.