Looks like a playback lol
and it sounds pretty annoying
but good for her!

who is she?

A brazilian singer. \o/

This is only a whistle note. A high chest voice is much more impressive.

She hits high notes, but if you've heard her actually sing she sounds terrible.

Not really. Higher "Chest" notes can be more easily accessed through heavy mixing. There have been several singers belting into the sixth octave per mixing.

I wouldn't even consider what she just did as whistling.

Whistling has a certain sound, vocal weight, and technique.

Hitting the highest note humanly possible is more impressive. I don't even see why you're downplaying the difficulty of whistling to the highest levels.

Glambert would MURDER that note

That's actually the very problem with singing now a days. Ever since Whitney Houston came out everyone in the music industry has to be a Mezzo-Soprano or at least have the capabilities of one (strong chest voice little else). It's annoying because you end up having a lot of artists singing outside of their register, fach and range in order to emulate the style of the preferred vocalist. Chest voice isn't everything although American Idol may fool the general public into believing that. There is more to singing then just that style of vocalizing.

Love that song in the background.