The Muslim EID holidays had just ended a few days before the attacks and while there were people celebrating, the footage was from several days prior to the attacks and was the EID celebrations. 'Blessed Day' celebrations from several days before which a news station, then the Internet took footage from and turned into venom and fire.
You are COMPLETELY wrong on this information and if you bothered to check this inoformation instead of accepting it on blind hatred, you would see that this information was not correct, but was twisted by some media outlets to create a story