Could just play on until the ball next goes out of play I suppose. Mind you if they played on and the other team scored I suppose they'd be pretty hacked off if it got ruled out.

The major problem for football is how and when you go to the technology.
In all other sports that use video technology, they only use it in scenarios where the ball is already dead.
You will never see the officials stopping play in Rugby League to check obstruction whilst the ball is still in play.
There was an incident when we played Wigan the other week were Tomkins broke free at the halfway line and made it to about 5 yards away from our line. When the replay was shown there was a blatent obstruction but because the try wasn't scored, the ref couldn't go to the video ref as the ball was still alive.
The pundits actually said that Warrington would have been better off if he'd have scored a try because it would have been pulled back to the halfway line for our penalty.

In football this kind of scenario can happen in far more situations.
A team could score a goal, but it isn't given as it looks like it didn't cross the line, but you then have two scenarios:

1. The ball goes immediately out of play so the ref can go to the video ref.
2. The ball stays in play and the game continues so the ref can't go to the video ref.

In the second scenario what do you do?
Do you do what happened in the example from our game above and just say tough luck, the ball is still in play so we can't go to the video ref or do you give the ref the power to stop the game at his own discretion to check it???

I don't think they'll ever go down the route of letting the ref stop the game to check as they don't even do that in any of the sports that already use video technology.
It can only go to the video ref when the ball becomes dead naturally, but then this could lead to a game in which both teams have a ball cleared off the line but it had actually crossed the line and one team were able to make use of the video ref as the ball went dead and the other team couldn't use the video ref as the ball stayed in play.

For me the best thing to do is to allow the FA to use video footage after the game and punish the officials for blatent mistakes like the weekend.
It is only by holding the officials accountable for these errors that I think we will see them improve their decisions.
As it stands at the moment, the FA take the stance that the referees decision is final.

As for the rugby league scenario, it is ridiculous that only live TV games have video footage.
Whether or not you agree with the rules of the game, all any player, coach or fan asks for is consistency week in week out. How can we ever have consistency when one week the ref has the advantage of video replays and the next week he doesn't.

So attach the sensors to the post/crossbar but position them a few inches behind the line!