The music of Imagine Dragons, big and dramatic, is built for arenas. The popularity of their Night Visions debut album created an audience demand that pulled the Las Vegas band into those behemoth venues before they had barely enough of a repertoire to fill a headlining performance. What they did have, in bushels, was a stage presence and a daring confidence that elevated their soon-to-be anthems high enough to satisfy the tens of thousands. So, when the group’s follow-up, Smoke + Mirrors, put the quartet back on the big league circuit, it was time to capture the magic on a DVD/CD set filmed in 2015 at a sold-out Air Canada Centre in Toronto. A near two-hour performance, one of over 100 on their world tour, is dominated by the songs of those two records; the biggest hit, “Radioactive,” slotted naturally in the penultimate position, and certainly a highest peak before the dénouement of “The Fall.” There is still a bit of stretching within the songs themselves, feeling not like filler, but more like the comfort of being able to expand the boundaries now that they have an opportunity. Imagine Dragons wants desperately to connect on a sweeping, emotional level and if that means drawing out the moment, they are happy to oblige. The technology of the day has made the advent of videotaping a concert (as opposed to filming) both cost-effective and common, but there is something that feels a little less grand about the choice for a viewing experience by such an ambitious band. Otherwise, the DVD of this momentous appearance presents these ascending alternative rockers in, now, their most fitting habitat.