In the video, Ariana's face was still puffy from oral surgery she had this week -- but she poured her heart out about the donut incident, saying ... "Not here to make any excuses. I'm just here to apologize."
Ariana added that seeing the video was a "rude awakening" ... and said she was taking responsibility, and apologized for letting her fans down.
As for people judging her? Ariana owned up, saying ... "I get it 100%, and I'm 22 years old, I'm human ... I make mistakes and I'm gonna learn."