Since I'm not all that certain about the Templars outside of Iberia, my response is going to be focused on the activities of the Order within the peninsula's borders.
First I will say immediately that, in Iberia, the wealth of the Templars had less to do with banking and usury and more to do with the patronage extended to them by monarchs and nobility, as well as wealthy confratres of the Order.
For instance, the first property given to the Templars was Castle Soure (Coimbra, Portugal) by Teresa, Countess of Portugal, in 1128. It is worth mentioning that Teresa's son, Afonso Henreiques (the first king of Portugal) was, a confrater of the Order. More about these later.
Donation of landed properties by monarchs and nobility was not abnormal. The second documented property that the Templars obtained was Castle Granyera in the County of Barcelona, which was given to them by Count Berenguer Ramon III. In 1135, Garcia Ramirez, King of Navarre, granted the Order joint ownership (with the Hospitallers) of the castle and nearby village of Novillas, over which the Templars subsequently gained sole ownership by granting the Hospitallers the village of Mallen in Aragon. To create an exhaustive list of the properties granted to the Templars would be a monumental task and the list would probably run into the thousands.
But I will mention probably the most outrageous of these donations. When Alfonso the Battler, king of Aragon and Pamplona died, he did so without heir and left quite literally both kingdoms entire to the Templars, Hospitallers, and Order of the Holy Sepulchre. They never obtained the property granted to them because the Aragonese and Navarrese nobility intervened, in strict violation of Alfonso's will, but it's still worth mentioning if only to illustrate just how enormous the royal favour towards the miltary orders often was and just how ludicrously wealthy they could become as a result of it.
I also want to come back to the aforementioned confratres because they are also an important factor in the wealth of the Templars. Confratres of the Order across Iberia were numerous. We know because we have surviving contracts of confraternity and lists of them in the hundreds if not thousands. We also have documents in which the confrater or some other patron bequeaths property to the Order. Sometimes these are horses, arms, money and even things like dresses and jewellery from woman patrons, but the overwhelming majority are grants of land (admittedly far more modest than the entirety of Aragon and Navarre).
So the question one asks is why did the Order, who didn't have a particularly strong presence in Iberia in the early to mid-12th century, gain so much favour from wealthy patrons? One explanation is, quite simply, the piety of the patrons. Another, and here there are hints from the locations of the landed properties donated to the Order, is that the patrons were trying to populate the frontier with the Moors and with other Christian kingdoms with fortifications garrisoned by the Order, thus absolving themselves and their heirs of the costly responsibility of doing so. My view is that both explanations are probably true.
Either way, what is certain is that through this patronage the Templars became enormously wealthy (and not just the Templars, by the way, but many of the military orders). It is a far cry from the rather cynical image that the author of your video paints, but this is not to suggest that there weren't abuses from which the Templars profited. I also don't buy into the now-famous accusations of occult practices, personally.