She's saying "standing in front of me", as the lyrics say.
She either slightly mispronounces it (exhaling a little more air than she intended to) or the microphone distorted it a little, which makes the T slightly elongate and sound a bit like an S, which is where your ear is getting a little confused: but she's definitely singing "standing in front of me"
I'm fairly sure in this case that it's mostly due to bad mastering of the audio for this video: You can hear the same effect on other T and D sounds in the song, along with a "hiss" on S sounds, which become over-exaggerated and sound a little like static. If you listen to the album version of the song, her mispronunciation is still there, but it's far less obvious due to better audio