In tennis , Hawkeye is used after the event to show the actual trajectory of the ball - I would like to have seen that here.

The 'clear' view of the ball crossing the line was from a camera which wasn't in line, and as such can be misleading. Mind you, if definitely looked from that angle that the ball had crossed the line and the goalie brought it back.

However, in the 'in line' photo they showed, the ball and the post overlapped slightly which would surely mean the ball wasn't over the line. So, there you go. Tin hat already in place.