Apostate prophet salutes everyone; Prophet said do not greet the Jews?

In answer to the video "The Infidel and The Jizyah"

The early Medinite Muslim community lived in an atmosphere of constant threat from inside and outside the city. They would never lay down to sleep except with their weapons with them and had to be in constant preparation for attacks from all sides, by the pagans of all Arabia, and their allies among the people of the book

8:60"And prepare against them what force you can and horses tied at the frontier, to frighten thereby the enemy of Allah and your enemy and others besides them, whom you do not know (but) Allah knows them".

The noble prophet, seeing himself as the guardian of the commumity was very often at the forefront in the case of a potential attack 

"Once the people got frightened, so Allah's Messenger rode a slow horse belonging to Abu Talha, and he set out all alone, making the horse gallop. Then the people rode, making their horses gallop after him. On his return he said, "Don't be afraid (there is nothing to be afraid of) (and I have found) this horse a very fast one." That horse was never excelled in running hence forward".

This is one of the features of defensive Jihad, as is done by most governments around the world today; dissuasion through constant military readiness of any potential enemy, known or hidden. In the case an attack is launched, then the Muslims counter attack will not delay so as to imperil the community. This deterring method creates an atmosphere where diplomacy might be preferred than risking confrontation. However even in such an atmosphere, Muslims themselves should never beg for peace when they are in an state of inferiority. This is simple common sense from a military perspective, as it would expose a weak mindset to the enemy who would in turn be further emboldened in his belligerent attitude. Only in a state of superiority should they go and seek peace from the enemy in order to avoid further bloodshed.

This is exactly what the prophet would instruct the soldiers to do when about to confront an open enemy. But should on the other hand the opposite party come with a peace offer then the believers are told to rely on Allah and "incline", ie be receptive to it

8:61"And if they incline to peace, then incline to it and trust in Allah; surely He is the Hearing, the Knowing".

God will strengthen and protect those who actively rely on Him, as He did in the past, in case their aggressors seek to deceive them 8:62. It is in such tense context that the prophet is reported to have said

"Do not precede the Jews and the Christians with the Salam. And if one of you meets them in the path, then force them to its narrow portion/narrowest path".

The background of this report is, as seen from other versions is the prophet setting himself for a military expedition against a Jewish tribe, leaving these instructions to those remaining behind

"Verily, I am riding against the Jews tomorrow, so do not greet them with peace and if they greet you with peace, then say: And upon you".

It clearly is a warning to remain distant and cautious of the enemy in times of conflict, openly signifying to him that no further avenue for deescalation between the parties exists. This is how the Classical scholars understood it, placing the report in their chapters related to war campaigns. The scholars further say the tribe in question was the treacherous and covenant breachers of Banu Qurayza. Outside this exceptional context, the Quran encourages Muslims to reciprocate in peaceful salutations.

Reciprocity in goodwill is so hardwired into the Quranic message that even when people meet and greet oneanother, the one answering should exceed the other in his greeting 

4:86"When a greeting is offered you, answer it with an even better greeting, or [at least] with its like. God keeps count of all things". 

The Islamic greeting is a supplication to Allah, that He might bestow peace on another. This known etiquette, which is a Muslim peculiarity, is a means by which people’s hearts are cleansed. It brings people closer together and reinforces their ties. Further, it is indiscriminate; regardless of who the one originating the salutation, one should answer in kind, with even a recommendation to sometimes precede the ignorant in wishing him peace 25:63,28:55,43:89.