In a video posted on YouTube, Howard is shown on a football field at a charity flag football game. As the national anthem plays in the background, Howard approaches a camera and says: "'The Star Spangled Banner' is going on right now. I don't even celebrate that (expletive). I'm black."
Howard's agent, Jeff Schwartz, did not immediately return a phone call seeking comment. Donnie Nelson, the Mavericks' president of basketball operations, directed questions to team owner Mark Cuban, who in an e-mail declined to comment.
The incident is the latest off-court problem for Howard, a fifth-year pro from Wake Forest who averaged 19.9 points and seven rebounds last season. He was arrested in July when police said he was drag racing at 94 mph in a 55 zone. A court appearance was scheduled for next week.
Howard was criticized last season for saying in a radio interview during a first-round playoff series against New Orleans that he occasionally smokes marijuana. Later that same series, he angered coach Avery Johnson by throwing himself a birthday bash after a Game 4 loss to the Hornets.