Youtube permite un links externos
Youtube deja la posibilidad a los partners de USA insertar links "click to buy" para los usuarios estadounidenses.
Ponen el ejemplo de comprar la banda sonora de un videojuego o productos relacionados con el video en cuestión.
"Today, we're taking our first steps to providing YouTube users with
this kind of instant gratification, by adding "click-to-buy" links to
the watch pages of thousands of YouTube partner videos. Click-to-buy
links are non-obtrusive retail links, placed on the watch page beneath
the video with the other community features. Just as YouTube users can
share, favorite, comment on, and respond to videos quickly and easily,
now users can click-to-buy products -- like songs and video games --
related to the content they're watching on the site. "
Vía Blog Oficial de Google
