The singer says in the video clip posted late Thursday that she's "disgusted" with herself. She adds that she didn't clearly convey her true feelings in her first apology - a written statement in which she ranted about obesity in America.
Grande came under fire this week when TMZ posted a video of her licking doughnuts and saying "I hate Americans. I hate America" inside a doughnut shop in Southern California.
The 22-year-old says, "Seeing a video of yourself behaving poorly that you had no idea was taken is such a rude awakening."
Grande says she wants to own up to what she did and "learn from my mistakes."