YouTube promises more measures to tame its comment trolls

'One of the hardest things to do is scaling openness, whether you run an internet platform or whether you run a country,' claims Robert Kyncl

" Interview part one: mobile, virtual reality and music

With more than one billion monthly viewers, YouTube is the biggest online video service - but in 2015, there are plenty of companies hoping to take a bite out of it.

Videos uploaded directly to Facebook are currently being watched more than 3bn times a day; startup Vessel is offering big YouTube stars more money if they give it three-day exclusivity on new videos; and Snapchat and Spotify have both expanded into video.

Related: Snapchat adds entertainment and news with Discover

Related: Vessel founder: 'Companies realise it's a chance to redefine the next generation of TV'

Related: PewDiePie, Zoella and who else? What the UK watched on YouTube in 2014

Related: YouTube and Google win lawsuit in free speech battle over anti-Muslim film