Youtube joins the Fifa world cup 2010 fever with adding a Vuvuzela button, which will add the sound of Vuvuzela to the video background. If you click on the button you can hear the sound of Vuvuzela. If the sound of the video is poor you will not be able to hear it if you select the vuvuzela sound.

Wikipedia about Vuvuzela

The vuvuzela (English pronunciation: /vuːvuːˈzeɪlə/, also known as lepatata (its Tswana name), stadium horn and plastic trumpet, is a typical 65 cm (2.13 ft) plastic blowing horn that produces a loud, distinctive monotone B♭3 note (the B♭ below middle C). A similar instrument, known as the corneta, is used in Brazil and other Latin American countries. Many types of vuvuzela, made by several manufacturers, may produce varying intensity and frequency outputs.[1] The intensity of these outputs depends on the blowing technique and pressure exerted.[1]