In game, there are two parts to the graphics - the UI part, and the background. A video for the song you're performing plays in the background and the UI part sits on top of it. The video is Full Motion Video that was made for the song, but it is not necessarily the actual music video for the song.
The in-game user interface takes the form of a series of columns that represent the different keys on the Beatmania DJ controller. One column is larger than the others, and that represents the scratch pad. When playing, the notes that are on the white keys show up as white dots and the notes that are played on the black keys show up as black dots.
And... the music. Beatmania is all about DJ remixes and club music. Some of the songs include: Attack the Music, Celebration, Do You Love Me?, Funkytown, La Bossanova de Fabienne, Lift Me Up, Metal Gear Solid Main Theme, Toxic, Virtual Insanity, You Really Got Me, Colors (radio edit), In My Eyes, Nemesis, Spin the Disc, The Cube and The Way You Move, among others. The song selections span the genres of Techno, Techno Pop, Ballad, Rave, Electronica, Soul, Jazz Electro, Hip Hop, Ska, R&B, Jungle, Warp House, Italo House, Trance, NRG, Disco and even 80's Revival. If you've wanted to try your hand at DJ'ing, there's a song in here for you.