Apparently the "Here Comes Another Bubble" video annoyed a copyright owner, and YouTube has taken it down. It can also be found here and here.
The EFF has a detailed discussion on fair use in user-generated videos such as this one. Legally, creators of parodies and other critical works are on pretty solid legal ground: these works are protected speech, not actionable infringement. The problem is that the DMCA forces hosting services to pull material and investigate later in order to protect themselves, often without adequate explanation to the user. A more transparent process is desperately needed.
P.S. Thanks to Keely for alerting me to the broken link.