Whinning noise when in Gear and using low accelerator

Please can somebody help me with my Skoda octavia 1.6petrol fsi. I took it to garage but they can fault find.

There is a whinning noise coming from left side of engine. I can notice this noise as soon as i cross speed of 30mph and it increases with speed. Best audible after 50mph.

I tried to record and the video is here 

The noise only come when using all of the below:

1. Little accelerator.

2. Car moving

There is no noise when i remove my foot from accelerator (even at high speed) or Speeding in neutral.. it has to be combination of little accelerator and speed.

It appears to come from left side of engine but i don't think it is bearing because, if I travel at high speed in neutral there is no noise. I took it to garage, they thought that it could be wheel bearing but on inspection they found bearing has no play.

Thanks.