Engineering excellence and user generated content (UGC) have propelled YouTube to Facebook-level reach, with growing viewing in all demographics and on the TV-set

However, the commercial limits and PR risk of its long-tail content model have prompted a diversification effort involving subscriptions and long-form content

Becoming a major part of Google’s revenue amid fierce OTT competition would require YouTube to be more flexible in its partnerships with the AV industry, and a more aggressive go-to-market strategy

Even with the decline in linear television viewing, online video remains a small component of total video consumption. The growth area is unsurprisingly SVOD; subscription video now makes up about two thirds of the UK's digital video spend.

Netflix is moving from an aggregator of content to a "channel" in its own right, increasing proportionate spend on original programming, something that the public service broadcasters are unable to do for differing reasons. Amazon had a tough 2017 for video, and are still struggling to create a hit.

New Nielsen audience data suggests that the long-term "library value" of Netflix's originals may be overstated, while the BBC's iPlayer continues to be hampered by not really having a library at all.

Almost half of Facebook’s impressive revenue growth and turnover is still reliant on the US, where user growth has slowed down

Among GAFA platforms, Facebook’s core business is the one most directly dependent on dwell time, but the metric for the crucial home market is clouded in mystery

The company has yet to create significant compensating revenue streams outside display advertising, raising the importance of international markets for Facebook’s future