Some brands and advertisers have been airing concerns over the impact of migration from traditional pay TV to OTT. This is a particular issue in North America where that migration is more like a stampede disrupting the traditional market for spot ads. Almost since the dawn of TV major brands have been able to rely on spot ads to achieve major shifts in awareness, perception or sale in a way no other medium could. That remains the case today but is a weakening phenomenon in the US as a result of the exodus to OTT. The number of OTT subscribers is expected to overtake linear TV in the US by 2020. The gap shrunk from about 30 million in 2016…