If you find and repair the leak or if the leak is so slow that it takes years to lose enough of the charge or if you are willing to top the system up from time to time then it is, IMO, worth the trouble but it is, ultimately, up to you to decide that. Now this assumes that the leak is on the high side. If it is on the low side after enough gas has been lost the suction side will go into vacuum when the compressor runs and air will be drawn in further reducing the ability of the machine to cool. To fully restore operation that air would have to be removed. But then in the video posted in No. 6 the guy admitted air when he tried to purge his gas line when the low side was in vacuum and it still worked to the point where it produced ice cubes.
While on the subject of the video: He stated that the gauge reading is an indicator of how full the system is with refrigerant. That's not true except crudely but the gauge can be used, along with the temperature reading, to determine how full the evaporator is and evaporator fullness is how the proper charge is set. The numbers on the scale on the gauge which is labeled R134A are the temperatures at which the refrigerant boils at the pressure indicated on the adjacent pressure scale. Thus, when he states his goal of charging to 5 psig we look at the R134A scale and see that -5°F is adjacent to 5 psig. That means that when pressure reads 5 psig the evaporator temperature will be -5 °F which seems a reasonable temperature for a freezers coil and probably realizing 5 psig is sufficient. If you want to do it right, though, you charge to 5 psig and then measure the temperature of the suction line where it exits the evaporator. That temperature should be about 6° ( the manufacture will have the exact number) above what the pressure gauge indicates as the boiling temperature. This indicates that the evaporator is mostly, but not completely, full of boiling refrigerant. If the temperature difference is greater than about 6 ° the evaporator is not as full as it should be and more refrigerant should be added.
He goofed and admitted air when he indicated that he had heard that one should purge the refrigerant fill line by loosening the connector at one end. That is true but he did it when the system was under vacuum. Do this but do it when the system is not running so it is all under positive pressure. Some refrigerant gas will be expelled from the end of the tube displacing any air in it which is a good thing. As the refrigerant is R134A there is no concern about the small amount released. Those cans of Dust Off and similar products work by blowing R134A onto whatever you are trying to clean.
