If you google mysql and youtube, there're many people talk about Paul Tuckfield's keynote presentation at MySQL world 2007.

However few noticed there's another great presentation of youtube mysql story by Cuong Do.
Seattle Conference on Scalability: YouTube Scalability

Cuong talked about the scaling problem of youtube's growing pain with in depth technoical detail.

Hidden feature of innodb monitor

It's quite fascinating to find out MySQL allow user to turn on/off extra monitoring information in a interesting way.

Create/Drop special tables like innodb_monitor and innodb_lock_monitor etc.

http://dev.mysql.com/doc/refman/5.0/en/innodb-monitor.html