MTV was once the most popular music TV station. MTV was founded in 1981 with a licence to broadcast only 180 music videos. It has promoted musicians like Michael Jackson and Britney Spears. Its influence on mass culture was so noticeable that the '90 generation is called by sociologists the MTV generation.
YouTube probably does not require Intro. For those who want to know a little bit, this website was created in 2005 and has immediately experienced enormous popularity. The first video on YouTube was Me at the zoo uploaded by user jawed. Currently, YT is uncle Google's company.