The two thugs probably never gave an indication of violence until it was too late for an appropriate response.
I guess the question I am beginning to ponder is...at what point would I say get back?
There are always indicators. The tricks are in knowing what to look for, and in how willing we are to listen to the little voice that's screaming
"something's not right." Too many of us feel it, but then tell ourselves that it's just our imaginations and either let danger approach us, or walk right into it ourselves. It's not our imaginations in most cases - it's our unconscious processing information that we aren't consciously looking at and giving us a warning.
Look at the videos again, and look at the offenders' eyes and body language. If folks you've never met before who have hard, predatory looks in their eyes like these guys do, approach you in an alley after midnight, there's no doubt you're going to be attacked if you don't do something right quick. The victims in this case may well have felt it too, but couldn't figure out how to get away before the attack began.
Folks who live by their wits on the street (LEO's, bad guys, and folks whose circumstances don't let them get out of bad neighborhoods) develop this sensitivity to a very high level. BG's can
feel the presence of an LEO, and an LEO can
sense a real bad guy at 50 yards - just about every time. It's a combination of looking at circumstances and people and picking up on eyes, posture, body language, gait, and when something is out of the normal rhythms of how things work and how people behave. There's an excellent book on this "sixth sense" called "The Gift of Fear" by Gavin deBecker, who specializes in protective operations for high profile celebrities. It is an outstanding collection of excellent information about how people can use the senses they now ignore to protect themselves, and how to know when your fear is based in reality and when you're allowing yourself to be startled by shadows. You'll probably want to ignore his opinion that folks shouldn't consider the armed option for self defense. It doesn't make a lot of sense in the real world, but that opinion appears to be based on an emotional reaction to a devastating incident he witnessed as a child as described at the beginning of the book. Give him a charitable pass on that one. The rest of the book is outstanding.
To return to your question of how do you know when danger is approaching, one very clear indicator is if someone keys his attention on you and moves in response to your movements or closes with you in an isolated location, you've been targeted - no ifs, ands, or buts. When he starts to close distance, that's your opportunity to challenge. Don't hesitate to move to a good position (near or behind an object of solid cover) and challenge with something like, "Stop there and state your business." Someone on legitimate business will explain himself or back away, but won't push it by insisting on approaching you. A bad guy could go either way - abort the approach at this point or press the closing maneuver. If he presses, you have articulable confirmation that he's up to no good. It'll go one way or the other very clearly at that point while you still have some options and maneuvering room.
If you wait until a BG closes to within 5 or 6 feet, you're gonna have a very bad day. As you pointed out, if you had been in that alley in Garland when the BG's made their final approach and asked for the cigarette, more likely than not, you (or I) wouldn't have made it out alive. At that point the BG has stacked too many factors in his favor and against yours. In a spot with no really good options, a move behind cover and use of one of the techniques Rex B mentions before the BG's weapon presentation move began was probably the only available route to a favorable outcome, and even so it would not have been a slam dunk. The earlier it was implemented, the more likely it would have been to have succeeded.
I do practice what I preach, and have used my senses and active intervention to come out okay from a number of circumstances where I or my wife was targeted as civilians but took action in time before the final approach was completed. None of those involved firing a weapon or inflicting injury.
The trick is to recognize the situation while it's still developing and before the BG has made his final commitment to attack. It's a learned skill, and it's not especially difficult if you're alert and integrate good info on what to look for into your everyday awareness of the world around you. The resources I've mentioned here are a pretty good place to start.
