Lower Youtube Quality

Hi,

i would like to have the option to lower the quality of background Youtube-Videos which is in general possible by append some parameters to the Youtube link (such as &vq=large or vq=medium etc.) to reduce the bandwith useage.
When i enter such a modified link, the input field will replace it with a plain youtu.de-Link without these parameters.
Any ideas?

Greetings,

Alex