This code, from the clumsy bird example, moves the world center at the same speed that the bird moves:
B4X:
Public Sub Tick (GS As X2GameStep)
Dim center As B2Vec2 = X2.ScreenAABB.Center
center.X = center.X + X2.TimeStepMs / 1000 * BirdXVelocity
X2.UpdateWorldCenter(center)