5. Sumner Redstone and the YouTube Guys

Frenemies since: Just about the moment Steve Chen and Chad Hurley (photo at right) launched YouTube in 2005, creating a haven for (among umpteen other things) clips from shows such as The Daily Show which are owned by Viacom. Viacom in turn is controlled by National Amusements, which is run by the octogenarian media mogul Redstone (left photo).

Acts of friendship: CBS, also controlled by National Amusements, has decided to make love with YouTube, not war, via its official CBS channel on the video site, where it willingly posts everything from David Letterman monologues to weighty documentaries on the Victoria Secret Fashion Show. It’s even begun uploading full episodes of a few old shows (MacGyver, anyone?).

Acts of enmity: Viacom isn’t content with just dashing off an infinite number of takedown notices to remove Jon Stewart and Stephen Colbert from YouTube–in March 2007, it sued the company for more than a billion dollars for massive copyright infringement. The suit drags on to this day.

Current state of the frenemyship: Terrible, if you’re talking about the Sumner Redstone who’s chairman of the board of Viacom. Copacetic, if it’s the Redstone who’s chairman of the board of CBS.

(Chen/Hurley photo by AP)