First of all, the title indicates how we as an industry are struggling to redefine the multiscreen world we now live in. When TV came, it was (technically) the second screen after cinema. But it quickly overtook cinema and became the first screen.
When I worked at The Coca-Cola Company, we often referred delusionally to how we were doing in “share of thirst” or “share of throat,” as we obviously were way beyond comparing ourselves to the soft drinks battlefield. And now TV and all other screens live, apparently, in a world where they vie for “eye-space,” per the Nielsen study title.
But it is true that we live in a world where multiple screens vie for attention and share at any given moment, often at the same time. I have said here before that using the general term “first screen” or any subsequent rankings of screen is useless, since the ranking varies by where you are and what you are using said screen for.