[Los Feliz Slim]

That Nike commercial is incredible.

Many feature film directors shoot commercials, and many started in the genre. Michael Bay directed the famous "Aaron Burr" Got Milk? commercial. Christopher Guest has directed a number of commercials over the years, including Washington Mutual, Kellogg's, etc. The documentarian Erroll Morris does tons and tons. Others: The Farrelly Brothers, Mark Pellington, Todd Phillips, Guy Ritchie.

These directors do commercials for the same reason everybody else does: money. A big-time feature director can get an incredible amount of money for relatively little time.