"The concept of 'watching television' is being redefined," said TDG's Senior Analyst Joel Espelien, who wrote the report. "It is being transforming from a social medium characterized by groups of viewers sitting in front of the living room television, to an individual medium defined by solitary viewers watching programs on smaller, more personal devices such as tablets and smartphones." This trend was being reinforced by the strong personal bond that has developed between consumers and their mobile devices, Espelien added.

This would suggest the drift from traditional TV to mobile will be strongest among younger viewers, who are likely to have the strongest affinity with their mobile devices. Confirmation of this has come from another survey from the world’s leading audience measurement company Nielsen, which reported a dramatic decline in linear viewing among so called Millennials aged 18 to 34.

Linear viewing has only just started falling among the general population, peaking in the US in 2013, but has been in decline some years among Millennials. However that has been at a fairly constant rate of 4% until late 2014 when it suddenly accelerated to plunge by 10.6% in the four months ending January 2015, according to Nielsen. Now only one quarter of quarter of 18-to-34-year-olds watch linear TV, compared with 44 percent of baby boomers born between 1946 and 1964 and so in the 51 to 69 age group.

Whether this is a blip or is sustained remains to be seen, but other findings suggest that the move away from traditional TV is even stronger among younger age groups still. UK communications regulator Ofcom has reported that TV consumption among 16 to 24-year-olds, the bottom half of the Millennials, has been falling faster than among the 25 to 34 age group. Then London based subscription media research service provider Enders Analysis found that TV viewing among 4 to 15 year olds tumbled by 22 per cent in the 18 months ending around mid-2014, the sharpest fall of any age group, with Millennials down 15 per cent.

Another study by digital media firm Defy Media suggested that it empathy with online content rather than mobile devices that was driving younger viewers to OTT services. The survey found that 62% of survey respondents reported online content as making them “feel good” about themselves compared with 40% reported for TV. According to the survey, 67% of millennials said digital delivers content they can relate to compared with 41% for TV, and 66% said they turn to digital content to relax versus 47% for TV.

Younger viewers identified YouTube in particular as a source of content they can relate to more directly than what is produced for TV. Such findings have serious implications for pay TV operators, since it suggests it is not enough just to deploy TV Everywhere and offer online access to reconnect with younger viewers. They may need to revise their content strategies as well.

But another aspect of recent surveys may be somewhat more reassuring for traditional operators. Although viewing may going to mobile devices it is mostly staying at home, which means that it is most likely to be going over the home Wi-Fi network rather than cellular. According to the TDG report 80% of tablet viewing and 50% of smartphone viewing occurs in the home, with little sign of that changing, despite the growing prevalence of faster 4G/LTE networks in the major markets, especially the US.

But irrespective of where it takes place, mobile TV viewing is increasingly being dominated by apps rather than browsers, which means that TV operators have to embrace these within their strategies. With growing Internet connectivity apps will increasingly find their way onto the main TV as well, creating new challenges since it means that more viewing will take place from inside some third party domain, owned by one of the big Internet players like Google or Apple.

But the more reassuring aspect is that this growth in mobile viewing at home is coinciding with a rise in second engagement with the main TV, which traditional operators can potentially exploit. A recent study by Millward Brown, part of WPP, the world’s second largest digital market research group after Nielsen, found that ‘of the total time screens are being viewed, simultaneous use with TV is taking place around a third of the time’. Simultaneous usage was even higher in some leading markets, being 41% in the USA.

There is a caveat in that of this simultaneous usage 62% is totally unrelated to the content showing on the first screen, being either browsing during ad breaks, at 42% of the total, or liaising with friends on social media about matters other than TV at 39%. But a growing proportion of second screen activity is now TV related, suggesting that operators, broadcasters and content providers are having some success with their companion engagement strategies. But there is clearly scope for a lot more engagement to bring the proportion of second screen activity that is TV related up closer to 50%.