Your questions are actually extremely complicated and you should ask yourself if you really intent doing something about what has already happened or if you simply want to avoid a repeat of this. To do something about what has already happened is going to be very difficult and costly and you will have many challenges such as where was the video shot? In SA or USA and if USA, where in the USA as laws differ from state to state.
You can click on this link to read up a bit more on the subject. Pay specific attention to the end where it discusses the situation around children.
I believe a strongly worded letter from an attorney might suffice to avoid a repeat of this incident.
I am not sure how USA laws will work and if they would require written consent from the father to travel over state lines, so I am no sure if she CAN do it.
What I can say is that your son will be able to use these facts, that the mother went beyond the fathers consent during this trip in his legal battle with her over custody. It may point to an attitude that does not take the father into consideration at all and also lying about it and may very well be detrimental to her case.
I hope this answered your question.
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