YouTube’s $14bn (£11.6bn) deal to stream National Football League (NFL) games marks the latest incursion by a Silicon Valley giant into territory traditionally dominated by broadcasters and pay-TV companies, as live sport becomes the latest battleground for audiences and profits promised by the streaming revolution. The Google-owned YouTube’s seven-year deal, which will see the world’s largest video platform take over the “Sunday Ticket” package of games held by the US satellite service DirecTV since 1994, followed an auction that included heavy interest from its fellow big tech company Apple. The deal is the latest in a series of commercially eye-popping deals by the NFL, the most expensive live sports rights…