"Beat music" can refer to several different unrelated genres.
1) A UK Rock / R&B sound that characterized many of the "British Invasion" bands of the 60's.
2) An electronic genre drawing from heavily from Instrumental Hip Hop, as well as Electronica, Jazz, and IDM. Characterized by many of the artists on the Brainfeeder label, such as Flying Lotus and Teebs.
1) Beat music, British beat, or Merseybeat (for bands from Liverpool beside the River Mersey) is a rock music genre that developed in the United Kingdom in the early 1960s. Beat music is a fusion of rock and roll, doo wop, skiffle, R&B and soul. The beat movement provided most of the bands responsible for the British invasion of the American pop charts in the period after 1964, and provided the model for many important developments in pop and rock music, including the format of the rock group around lead, rhythm and bass guitars with drums.
2) Beat music is a general term for a large variety of different sounds that have come out of Los Angeles (and around the world) since the mid-2000s. The music often has off-tempo grooves and complex percussion, but it really only describes a sound that exists in the space between a Hip Hop or R&B instrumental and an electronic song. .