A camera that never stops watching
The most obvious effect of video review is the handful of decisions it overturns each week, but its larger effect is behavioural, produced by defenders knowing that every contact in the penalty area will be viewed again in slow motion from multiple angles. This has visibly changed body shape at set pieces and during challenges, with defenders keeping arms tucked closer to the body than they once did, not because the laws on handball changed dramatically but because the certainty of review made previously tolerated risks no longer worth taking.
Offside margins and attacking timing
Precise offside review, capable of adjudicating margins invisible to the naked eye, has altered how attackers time their runs in behind a defensive line. Where a striker might once have timed a run to beat the offside trap by a comfortable distance, fine-margin review rewards timing a run as close to the line as possible, since the smallest advantage is now enough to stand. Defensive lines have responded by holding their shape with greater precision, aware that a half-step of carelessness is now measurable in a way it never used to be.
A cultural shift, not just a rule change
The cumulative effect is a defensive culture that behaves as though under permanent observation, which changes conduct even in moments no review ultimately examines. This is arguably the more significant legacy of video review compared with its headline function of correcting errors: it has trained a generation of defenders to treat marginal contact and marginal positioning as risks not worth taking at all, a caution that shapes matches long before any official actually reaches for a replay screen.