As someone mentioned earlier the safety aspect of the semi-educational video is missing, (see above). Getting under a trailer supported by one hydraulic jack could prove Darwin’s theory in the working. One critical aspect of working around brakes
is to not contaminate them with even minute amount of grease. Touching any frictional area (including electromagnetic lever area) with greasy fingers is what I would consider contamination and is shown on this clip. If grease gets on metal frictional areas the surface needs to be clean with brake cleaner. Any grease on frictional materials calls for its replacement.
Adding a nipple, you are probably thinking about Trailer Buddy or equivalent protectors. These protectors replace solid metal hub cap and are design to keep grease pressure within the hub bearing space to prevent water entry during wheels immersion in water. Their primary use is on boat trailers. Removing and putting new grease still requires full disassembly.
There is the system called EZ-lube by Dexter with nipples mounted on spindles. You need EZ-lube axles so if you don’t have them it would be expensive. EZ-lube allows grease replacement without bearing disassembly. During lubing grease moves from the grease nipple through the spindle to the large bearing and then back trough the bearings flashing old grease out. When you see new grease coming out you are done. You can diagnose the health of the bearing without disassembly by evaluating smoothness of hubs rotation and how contaminated is the flushed out old grease. I had this system on my boat trailer (3 axles) for 11 years and never had to disassemble the bearings.