From E Pluribus Unum’s diary at RedState:

For anyone unaware, YouTube has pulled a John McCain campaign ad
critical of Obama’s use of ‘lipstick on a pig’ in an obvious
counter-play off of Governor Sarah Palin’s joke regarding ‘hockey
mom = pit bull + lipstick.’ Why was the ad pulled? Because of a
complaint from CBS News to YouTube regarding the use of a Katie
Couric clip in the ad. In general, YouTube is quick to pull
material in response to ‘copyright violation’ complaints.

H/T to
Ben Smith at Politico, the YouTube ad page now says “This
video is no longer available due to a copyright claim by CBS
Interactive Inc”. As far as I know, CBS has every right to
protect every millisecond of copyrighted material they possess.

However, CBS spokesperson Leigh Farris confirms that the
motivation was a political one, saying, “CBS News does not
endorse any candidate in the Presidential race. Any use of CBS
personnel in political advertising that suggests the contrary is
misleading.”

What has CBS had pulled from YouTube, what have they allowed to remain? I honestly don’t know.