Like a lot of people who’ve spent time writing about cinema, I have mixed feelings about the related form of gallery-based video art. At its best, it can unshackle the full expressive potential of the moving image from the sometimes limiting constraints of narrative film-making. At its worst it just looks like shoddily made, badly performed indulgence. Both of these poles and plenty in between are on show at Signals: How Video Transformed the World, running at New York’s Museum of Modern Art (MoMA). The exhibition features work from the last six decades which (the introduction claims) “reveals the ways...