High Pitched whine, even when stopped?

[lurky]

Hi
2007 boxster, Half way through my commute to work this morning I noticed a high pitched whine coming from my car.
Today is a rainy day, not sure if that is related.
This noise immediately goes quiet whenever I accelerate, and starts up again when not accelerating.
I though the noise might be brake related but then I noticed that it continued even when I stopped. There are No messages on the dashboard.
So I made it to work and took this video where you can hear the sound ... Anyone have any idea what it could be? Is it dangerous?

https://www.youtube.com/watch?v=nkvDrXrKWMA&feature=youtu.be