A new message claiming to be from the group responsible for the Sony Pictures hack appears to mock the FBI, which named North Korea responsible for the attack on Friday.

“The result of investigation by FBI is so excellent that you might have seen what we were doing with your own eyes,” the message posted on Pastebin reads. “We congratulate you success. FBI is the BEST in the world. You will find the gift for FBI at the following address.”

The message — titled a “Christmas gift to FBI” — was posted on the file-sharing site on Saturday and links to a YouTube video called “you are an idiot!” that was uploaded in 2006. The two-minute clip includes text in a foreign language.

Despite the message’s familiar format and broken English, it’s unclear whether it was indeed posted by the Sony hackers, who call themselves the Guardians of Peace, since a mass email wasn’t sent to journalists as usual.

North Korea denied that it was behind the cyber-attack earlier on Saturday and offered to launch a joint investigation with the U.S. into the hacking in order to prove its innocence.

The country had first threatened to retaliate months ago if Sony released “The Interview.” After the threat, numerous internal documents, personal information of studio employees, unreleased film and emails were leaked online within the last month. The hackers’ latest round of emails warned of 9/11-style violence, prompting the studio to pull the comedy from theaters.

President Barack Obama said during a Friday press conference that Sony made a “mistake” in dropping the movie. The studio has since defended its decision.