I think in all sports, there is a respect for the human computer of the mind to break down and evaluate signs being stolen.
But if you can't see the difference between video taping and doing it on sight, then I don't know what to tell you.
Given one real time glance versus being able to rewind, review and disect the sign and you can't see the difference?
Is there a difference between watching the game from the sideline and being able to disect the game in videotape? Sure, but we allow it. I don't see the difference between allowing a coach to watch videotapes of the game, but not allowing a coach to watch a videotape of sideline coaches.
With regard to videotaping, which before being called videotaping was called filming, as it dated back to at least the 50's if not sooner than that. Film originated as probably as much as a reason to know what you were doing wrong as to know what your opponent was doing. Other sports GENERALLY haven't lent themselves to videotaping as much as the NFL, though its evermore becoming in vogue in other sports. Football, being a weekly affair, as always lent it self more to that. So apart from the tradition of film, the difference is, film analysis is done as means of evaluating and predicting tendencies.
The Nickel back plays 8 yards off the weakside for a blitz, you pick that up, it's the kind of thing thats in the public domain. Its predictive but not guaranteed.
If you decipher signs through videotaped analysis, you cease to be predicting, you are knowing EXACTLY what is going to be called. There is a difference, and a pretty major one where I stand, but I guess we'll find out where the league stands.
I could study a teams offense for a season and write their playbook. I could also just break into their office or bribe their player and take it. By your logic, I've acquired the knowledge of their plays either way and there is no difference.