The hotel said in a statement that it had fired the person "responsible for breaching the security policies of the hotel and recording the confidential CCTV video released by TMZ."
"The Standard has already terminated the individual and will now be pursuing all available civil and criminal remedies," the statement added.
The video, in which Solange attacks Jay Z as Beyonce watches, has launched endless speculation. Some reports contend that Solange was intoxicated, while others claim that Jay Z wanted to attend Rihanna's after-party without his wife.
The hotel promised to recover the source of the leak shortly after TMZ published the video.
"We are shocked and disappointed that there was a clear breach of our security system and the confidentiality that we count on providing our guests," the Standard said. "We are investigating with the utmost urgency the circumstances surrounding the situation and, as is our customary practice, will discipline and prosecute the individuals involved to our fullest capacity."
Though the unidentified employee lost his job, Page Six said Tuesday that he or she was paid $250,000 for the footage.