Never heard these renditions before, and they certainly strike a chord with me.

Perfect melancholy for these days, and conjuring reminiscences of the Church at the height of her strength.

An army -literally- in battle array.

I can well imagine these Templars marching through the deserts by the thousands, chanting these songs, and striking fear into the hearts of the Islamists.

What a sight that must have been!

The Knights Templar degraded into a secret society similar to the Cathars and Fɾҽҽmαsσɳɾყ.

http://www.askwhy.co.uk/christianheresy/08291KnightsTemplar.php

In summary, the charges against the Templars were:
    The Temple houses cover every possible crime and abomination.
    Each Templar on his admission swore never to quit the order, and to further its interests by right or wrong.
    Novices of the order, after taking the oath of obedience, were obliged to deny and otherwise blaspheme Christ, and to spit, and sometimes also to trample, upon the cross.
    They then received the kiss of the templar, who officiated as receiver, on the mouth, and afterwards were obliged to kiss him on the anus, on the navel, and sometimes on the penis.
    Many statutes of the order are unlawful, profane and contrary to Christianity. The members are forbidden under threat of imprisonment to reveal them.
    The heads of the order ate in secret alliance with the Saracens, and they had more Mohammedan infidelity than Christian faith. The order works to deliver the Holy Land to the Saracens, and favours them more than Christians.
    The heads of the order are addicted to debauchery, heretical, cruel and sacrilegious men. They kill any novice who discovers the iniquity of the order, and tries to leave it, and bury the body secretly by night. Anyone objecting to it is punished by perpetual captivity. They teach women who are pregnant by them how to procure abortion, and secretly murder new born children.
    The Master is installed in secret with few younger brethren present. It is because he repudiates the Christian faith, or does some similar blasphemy.
    They are infected with the errors of the Fratricelli. They despise the pope and the authority of the Church. They scorn the sacraments, especially those of penance, and confession. They pretend to comply with the rites of the Church simply to avoid detection.
    They sometimes worshipped a cat, which appeared amongst them in their secret conclave.
    They practised ɧoɱosɛҳųαƖ acts together, refusing normal sɛҳuąƖ intercourse.
    They had idols in their different provinces, in the form of a head, having sometimes three faces, sometimes two, or only one, and sometimes a bare skull, which they called their saviour, and believed its influence to be exerted in making them rich, and in making flowers grow and the earth germinate.
    They always wore, bound about their bodies next to their skins or about their shirts, a cord which had been rubbed against the head, and which served for their protection.
    No vice or crime committed for the honour or benefit of the order is held to be a sin.

http://www.askwhy.co.uk/christianheresy/08291KnightsTemplar.php

I have doubts that these are templar chants.  I think the templar theme is more an example of click bait.  These are simply old roman chants sung by orthodox(maybe catholic, maybe not) monastics.  Rocor was using one of these "latin" chants in a promotional video of theirs.  They are certainly worthy of listening.  You are not going to be promoting or become a templar by listening to them.