From what I heard, Star Sports will be broadcasting some of the matches in India. For other countries the broadcasters are - Sky Sports in New Zealand and United Kingdom, Gazi TV in Bangladesh, Ten Sports in Pakistan, Fox Sports in Australia and SuperSport in South Africa. But I have no idea about how many matches will be shown live. The interest has gone down considerably. Just one more week to go before the opening, and there is hardly any coverage in the mainstream media or in the sports channels.
Main reason is too much cricket. All year we have t20 leagues plus icc tournaments there is hardly any interest left in U19 and domestic cricket. Trend these days is try to make it to any T20 league and from there players are picked for national team that play test and odi.
Cricket lovers watch all types of cricket. Also after the start of the under 19 world cup, we can see people discussion's on those matches on this forum too. This shows that there is still interest for under 19 world cup.
I am also following these matches. So far the Indian team looks quite strong and one of the favorites for lifting the cup.