Today (April 23) marks the 9th birthday of YouTube. Here is the very first video ever uploaded to the website. It's hard to believe this is what started a worldwide obsession with the video sharing site.

The 18 second video features YouTube co-founder Jawed Karim at the San Diego Zoo. Karim and his partners Chad Hurley and Steve Chen sold the company to Google for an estimated $1.65 billion.

Take a look at this compilation of the first 20 videos uploaded to the site. As you watch, you'll notice that nine years later, many of the videos uploaded to YouTube really haven't changed that much. On the other hand, we are grateful for the videos that have.