Mel B performed with flair at the Spice Girls' 30th anniversary concert in London.
Fans packed the O2 Arena.
Melanie C said the show was moving.
The night was marred by a reported feud inside the group recently.
The dispute centres on leadership and payments.
The event marks three decades since the group first burst onto the scene.
Later that day Mel B appeared as a stand‑in judge on America’s Got Talent.
A teenage singer took the stage and earned the show's golden buzzer right after the final note with applause.
The buzzer sent the act directly to the live shows.
Cowell pressed it instantly.
Mel B said the singer showed remarkable confidence.