Question On Spot Challenges

[links18]

The rule is you have to challenge a specific thing. So if you challenge a spot for the line of gain, they must move the ball to/past the line of gain for the call to be reversed.

But once you challenge, the entire play is open to review, isn't it?

 

[lurkercowboy]

What about that "under the hood" view on the big screen at the stadium. Is that exactly what the ref is seeing?