Mobile views on YouTube have quadrupled in the last 18 months, the company’s global head of content Robert Kyncl revealed at the Abu Dhabi Media Summit, with mobile making up half of all viewing in some markets.

Kyncl said that mobile devices now generate a quarter of all traffic across YouTube, a fact first revealed by YouTube’s director of product management Shiva Rajaraman last month. What is new, however, is the incredible rate of growth over the last year and a half, which Kyncl called “a massive consumer shift” (via Fierce Mobile Content).

Kyncl said that mobile should not be simply seen as a second screen experience. “Mobile] is the first screen, so when you talk about the second screen, you are talking about the television,” he said.

“When you’re making your selections on your phone and you’re sending them to the TV – something that is coming very soon [on a mainstream basis] – when that transition is seamless, this becomes the first screen.”

Kyncl also noted that in some markets, like Saudi Arabia, half of all YouTube consumption comes via mobile.

YouTube has become unsurprisingly focused on mobile of late, releasing a standalone YouTube app through the App Store in September (in response to Apple removing the native YouTube app from iOS 6) and gearing up for the launch of a mobile music video product.