It is a staggering increase - double the views it had in April - which appears to dwarf the billion views YouTube clocks up daily.

Facebook's aggressive push into video will surely delight advertisers who can promote their products alongside popular clips.

But not everybody is convinced Facebook will eclipse rival YouTube.

How did Facebook video grow so quickly?

Making clips play automatically, a new video tab in mobile, and suggesting more videos to keep people watching will all have contributed to Facebook's mammoth viewing figures.

Facebook also prioritises video in the news feed, or as its founder Mark Zuckerberg puts it: "Helping people discover content that they hadn't really asked for."

But the company has been criticised for registering a video as "viewed" if it plays for just three seconds.

"It's counting you seeing the video, essentially no more than you scrolling past the video in your news feed, as a 'view'," said Tom Ridgewell, who posts popular animations on his YouTube channel. "Those aren't true statistics."

YouTube has already moved away from views as a way of judging how engaging a video is, instead focusing on how long its viewers spend watching videos - "hundreds of millions of hours" every day, it says.

But Facebook has defended its focus on views over watch time. In August, it said three seconds was an acceptable metric because it showed a person's "intent to watch".

Is Facebook Video a threat to YouTube?

One of the problems Facebook is trying to tackle is that its video offering is often a fleeting experience, but longer videos typically attract more valuable advertising.

It is a situation the site's founder Mark Zuckerberg acknowledged on Wednesday.

"The more natural starting point for us is shorter form content," he said, describing the news feed as "not the place where you're necessarily going to see a TV show and then watch an hour-long clip right there".

In September, the average duration of the top ten videos on Facebook was about a minute, according to NewsWhip, a site that tracks the "social velocity" of online content.

"The big question for Facebook is how it can attract the sort of premium, high-quality videos that people want to sell ads against," said Joseph Evans, digital analyst at Enders.

"If it can nail that, it does start looking like a threat to YouTube.

How will Facebook attract creators?

"There's a certain class of content which is only going to come on to Facebook if there is a good way to compensate the content owners," said Mr Zuckerberg.

The site has already promised new content-matching tools to spot piracy, after research by advertising agency Ogilvy found that 73% of the most popular videos on Facebook in June had been ripped from other websites.

But the site is only just starting to share advertising revenue with video creators, and only with selected partners in the US for the time being.

"I have very little to gain from putting my videos on Facebook," said Mr Ridgewell.

"I don't care about gaining superficial views from a completely passive audience. This is a business for me, I'm investing a lot of money in this content, and I can't afford to throw it away on Facebook. It's expensive to make."

Competition between the online video giants is likely to get fierce and it is clear that Facebook's move into video is not a short-term experiment: the company has a "clear roadmap" for the next few years, according to Mr Zuckerberg.

Mr Evans thinks both sites can co-exist peacefully - at least for now.

"YouTube is where people go when they know what they want to watch. It is better at long content, whereas a funny video to pass the time performs better on Facebook," he said.

"I don't think it's winner takes all at the moment."

(bbc.com)