Client of 1mbps youtube PCQ 2mbps but consuming 7mbps

Hi
I have assigned 1mbps for a client and create 2mbps limit in PCQ for youtube
for buffer free playback. But now problem is some of my client download from
youtube and get 7mbps+ when he download more then one video from youtube.

How can i prevent it so that he can not get more then 2mbps if he download more
than one video from youtube.

Thanks