The Thai government approved a controversial change to curb its lively market in pirated music and videotapes. The change will be debated in Parliament soon. The move is in response to U.S. threats to eliminate Thailand's rights to ship goods into the United States at a low tariff rate. Thailand's Copyright Act of 1978 protects books and works of art but excludes films, music and computer software. A spokesman gave no details about the proposed amendment and could not say whether it would also cover the lucrative market in pirated computer software.