If you don't want to watch the video, feel free to read the rather small synopsis below of what would have happened. It's not a huge deal, but it could spoil what ended up happening in general for those of you who haven't played it.
The ending basically involves Joel and Ellie four years after the game. Joel gives Ellie a guitar as a gift, and performs a song. Ellie picks up the guitar and attempts to learn to play. That's it. It's basically a "goodbye" to the two characters in a less strained fashion, as per the game's director.
can cause it. You can fix it by adding *.disqus.com to your whitelists.