i want to address a few issues that were brought up. the predators post said (paraphrased)
the girl notices and goes from walking to walking briskly, to running. she tires to quicken her pace and lose me. meaning she is taking a path that is purposeful to prove to herself that he is following her. notice he said she quickens her pace to a run. i do not think anyone meandering though a busy area like a shopping mall is going to be running. when someone is following you in this manner he is purposeful and will be looking at her at certain points. now i do not want to speak for the other gender but i believe we all know when someone is making glances at us and i think women are more in tune to men looking at them in undesirable ways.
while a theoretical case could be made that filming the potential stalker might entrap innocent men, i find it highly doubtful in the real world. sexual predators do not want to be caught. the last thing they want is to be on camera. (it ruins any alibi of "i wasnt there, it wasnt me") they will find another target if they feel in danger of being exposed. in the case it really was an abduction there would be photographic evidence for police to use for investigations.
as far as confrontation, i do not think it would escalate. ill have to think about this some more but i do not think so. this is about a young girl i have a feeling its not going to turn into a fight but i could be wrong.
also it doesnt have to be confrontational. i do think that approach works well in many cases but it takes courage. the girl could do what girls tend to do...take selfies.

consistently pointing the phones camera lens in his direction. the point is he is going to know he is on camera and the hope is he will abandon his target for someone else.
using the phone camera is a tactic, it doesnt have to be Facebook live, it could be used anyway the person feels will work in that particular situation.
the underlying principal is to "create a strategic stalemate". this means taking defensive actions as soon as possible. calling the police because you think someone is following you would not be my advise. first off, most times the victim is not sure where that line is , when should they call. its like having chest pain.
do i call the doctor? do i call an ambulance? i dont want to look like a fool calling the ambulance and the EMT"s for heartburn. maybe ill wait a bit and see if i feel better.
sometimes its obvious, most times its not.
so what i advise is to react as soon as you
think something is happening. but that doesnt mean press the panic button and call the police (who are not going to be much help anyway). you dont jump in absolutes. you make smaller incremental moves creating that "strategic stalemate" where it will cause a reaction of either defusing the attempted attack or forcing the assailants hand to reveal himself if he is determined. in which case you now know the extent of the danger and can jump from 0 to 60 in flight or flight mode, color RED. by acting in this manner you should have put yourself in a better position to defend yourself. Cross the street, leave the premises, move closer to the door, position yourself to conceal your draw, cover/ concealment, get ahead of the crowd. its not yelling fire in a movie theater, its small and subtle so if its a false alarm you can recoup and go about your day. but the sooner you react the more effective it is.