Animate within Manipulate function is considered a unsafe dynamic content by Mathematica 8

If one has Animate within Manipulat in a notebook, one gets the warning

This file contains potentially unsafe dynamic content.

even if it is located at TrustedPath.

To avoid this warning, use only Manipulate. Turn the animation variable "t" to one of the control variables of Manipulate and set ControlType->Animator. Otherwise, wrap Animate function inside with DynamicModule.