"To celebrate the launch of The Last of Us Remastered on PlayStation 4,Sony and Geoff Keighley put on a live performance yesterday featuring key scenes and musical selections from the game. In case you missed it, Sony archived it on YouTube. Just make sure to scrub past the 30-minute countdown someone forgot to delete." - Ripped from This GiantBomb Article
There are of course, big spoilers in this video. The audio is bit messed up in places (because of it was live stream) so I would suggest increasing your volume. I posted the video starting at the 30 min mark as that is when the show begins, the minutes before that was just a countdown screen for the live stream. Enjoy!
**MAJOR SPOILERS FROM HERE ON OUT!**
There was an ALTERNATE ENDING only shown to the folks who watched it in the theater. Neil Druckmann (Creative Director) said this ending would NOT be made into any other type of form and would only be shown to the audience. He asked that no one filmed it.(No one did) This image was taken to show proof of its' existence
Neil said this is the proper goodbye to Joel and Ellie.
Ripped from This IGN article
The events that take place in this scene either happen day one after the ending of The Last of Us OR take place 4 years after the ending. This is just speculation made by the audience.
"Joel is talking to Ellie in her room at Tommy's, explaining that Tommy is trying to set him up to marry a girl named Esther. According to various accounts of the scene, Ellie is acting distant and reserved, until Joel pulls out a guitar and sings a song (which Joel's voice actor Troy Baker performed live.) Joel tells Ellie a joke, and the pair laugh together, the tension broken. Joel leaves the guitar with Ellie as a gift, and the scene ends with Ellie alone on her bed, strumming a chord."