It's 1911 on YouTube! That's YouTube's April Fool's gag—push a little "1911" button on the screen, and you get an old-timey version of your video, complete with a piano-roll soundtrack. This joke is not appropriate for all videos.
As The Daily Show's Daniel Radosh pointed out via Twitter, YouTube apparently neglected to anticipate the extent to which a mock silent-film treatment is not at all funny when applied to videos showing sad and horrible things.
So video of your dad hitting himself in the face with the tetherball in the backyard set to ragtime music? Funny! Video of 9/11? Not funny! (While we were busy grabbing examples of how this trick can be misused, YouTube seems to have caught on, and removed the "1911" functionality from a bunch of 9/11 videos.)
Anyway, here are some other not-at-all-funny April Fool's Day jokes from YouTube:
What would the Japanese tsunami have looked like in olden-times?
This one has little dialogue cards just like a real silent movie.
This one is much improved.