Information:
This is a popular music/variety show that is hosted by Japanese comedy duo downtown (Matsumoto Hitoshi and Hamada Masatoshi) since 1994.

This program has probably seen more format changes from the time period of 2003 to the present, than any other Japanese music program that comes to mind. The classic format was that each show would feature approximately five different guests. Downtown would bring them all out onto the studio stage at the beginning of the program, introduce them, and make jokes/pick on them (which Downtown is famous for doing, since they're comedians). After they have all been introduced, one guest/group would be selected for a more lengthy, sit-down interview with Downtown. They would then have an in-studio performance. The rest of the guests would get a shorter, stand-up interview with Downtown, and then they would do their performances. There would often be a break around the middle of the episode to take a look at the best ranking CD singles in terms of sales, karaoke, and several other factors. (Though in time, this ranking would be moved all over the place. Examples include the very last segment of the program, and at one point, even rolling during the end credits)

The changed format (that started to take place somewhere around 2004) consists of having one main guest musical guest/set of guests, who is the "champ". They have a lengthy sit-down interview with Downtown, and throughout the course of the interview, various other (usually non-musical) guests will be brought out to interact with them, and assist in their interview. There are also a couple of other segments that are now seen with some regularity. These include hoshi no restaurant (where two different musicians will be brought with Downtown to a studio restaurant, and they will all be served two reccomended three-course meals (one reccomended by each artist)), and The Legends (where Downtown will bring out one to three older artists, interview them, and take a look at some clips from their pasts). There have been many other segments that have come and gone in relatively quick amounts of time.

After this format ran its course for a couple of years, Fuji TV obviously decided that it was time to get back to the more traditional, and time tested format. In 2007, Hey! Hey! Hey! had a "renewal", which would take it back to its classic format.

Regardless of the show's ever-changing format, it remains an extremely popular show, as Downtown is one of Japan's most beloved comedy duos.