Confirming the authenticity of the recording could prove difficult. The original recording is presumably in the possession of TMZ. The NBA, as a private business, has no subpoena power to force TMZ or any other entity to turn it over. TMZ may be reluctant to share the original recording, especially if it was obtained on the condition that it would not be shared. TMZ may also be reluctant to share the recording because the recording itself could be unlawful.
Under California penal law, it is a crime to intentionally record a confidential conversation without the consent of the person or persons being recorded. This type of eavesdropping also empowers victims of the unlawful recording to sue for money damages. TMZ's own exposure to liability is far less than the person or persons who made the recording. TMZ is a media company with broad First Amendment rights, especially on matters that are newsworthy. Still, media companies can be sued for publication of private facts, and Sterling, an attorney by trade, could consider legal action.