title: Which database does Youtube use at the moment?
body: <p>I hope anyone can help me out in this topic, even if it's not a specific programming question.
  I'm writing a bachelor thesis, where I compare MySQL to MongoDB and I want to write something about Youtube, as the platform has to handle many requests with heavy dataload.
  The only good resource which I found was this video: <a href="http://video.google.com/videoplay?docid=-6304964351441328559" rel="nofollow">Seattle Conference on Scalability: YouTube Scalability</a></p>
  
  <p>As the conference was in 2007, I can imagine there were some updates regarding to the database.</p>
  
  <p>The last information that I have from this talk is that the thumbnails are stored in a BigTable database and the metadata in MySQL. Are there any changes since then?
  Where are the videos stored? Is there an entry in the MySQL table, which refers to the stored video?</p>
  
  <p>Thanks in advance for the answer!</p>