What's behind Alonso's F1 test return

Fernando Alonso was back in the Formula 1 paddock this week, as McLaren announced he would take up an ambassadorial role with the team and will test its 2019 car. Alonso and team boss Zak Brown then addressed the media about the news, and from F1 testing in Spain Ben Anderson and Scott Mitchell explain the background to this story, plus what it tells us about Alonso's motivation and how serious he still is about F1 despite not being on the grid this year