Nothing wrong with re-plating the studs on the cam housings because they're not under any considerable load. They're just sealing the valve covers. Basically all of the hardware in the cam housing can be plated with no concerns- studs, banjo fittings, spray bar "setting" plug are all fair game.
The cam end plug Neven911 is referring to is the steel "freeze" plug in the end of the camshaft housing bore (where the camshaft itself resides). He's not referring to plating the actual spray bar bore plug, which is indeed aluminum and so is the spray bar aluminum.
The steel plugs do tend to rust and sometimes can be a bit stubborn to knock out because they're a moderate press fit and also sealed around the perimeter with a thin coat of the famous orange Loctite 574 goop. I'd be cautious about reusing them if you have to knock them out hard. The center can deform a little bit and you can also lose a little bit of the "bite" in the plug diameter from years of the steel relaxing its shape. Notice how easily he taps in the new steel plug in the video. That's not to say that new plugs should require a ton of force to drive in place. I'm just saying that a reused plug sometimes won't go back in as tight as it came out. The steel is mild stamped steel, not spring steel, so it's not difficult to deform. They're cheap to replace and therefore I feel it's wise to just buy a couple of new steel plugs.
I would suggest only removing the spray bar end plugs to get a look inside for any crud that should be removed. Leave the spray bar in place and clean it in-situ. The reason I say that is because the spray bar is sealed to the housing at the factory to ensure there's no leakage at the locations where it feeds oil to the camshaft journals/bores. So don't disturb the seal if you don't really need to. Because when you remove the spray bar, it takes a bit of patience and care to not damage the end and scrape the heck out of it as it's coming out. After doing a number of these myself, I tend to think the factory assembly process heated up the cam housing to expand it and then the "cold" spray bar was inserted to go in nice and easy. Because when you do a cold removal, the spray bar comes out with some significant resistance.
When you watch him reinstall the spray bar in the video, notice how easy it goes in. He cleaned the spray bar exterior and also ran the brush through the cam housing to clear any debris. Doing that loosens the fit of the spray bar in the housing, and thus the oil feed (oil pressure, mind you) to the cam bearings. This is why I say leave the spray bar alone if it looks OK in place. You can look down the spray bar interior with a bright light and see if there's any crap in there while it's in the housing. Note that since the holes in the spray bar are drilled, it's always going to look like there's something in there on account of the rough edges created by the drilling. This is why his method of running the brass brush through the spray bar while it's in the housing is good practice. The brush can knock loose some of that "flash" material. However, after brush cleaning, use some brake cleaner and a piece of stiff wire to clear all of the pin holes and cam bearing holes to ensure any loose material caused by brushing is removed.
I wouldn't recommend stainless studs. Stainless and aluminum don't agree with each other. The dissimilar metals induce galvanic corrosion and you end up with studs frozen into the housing for the next person to deal with. The reason is because aluminum and stainless steel have anodic indices that are somewhat far apart on the scale of materials (see listing of metals in link below)
https://en.wikipedia.org/wiki/Galvanic_corrosion
Stainless steel isn't identified on the list but it's basically chromium steel. So the aluminum corrodes more easily when in contact with stainless steel. This is why the steel studs are plated with zinc or cadmium because the coating brings the anodic indices closer together at the bottom of the list. The plating on the studs is also to protect the studs themselves, regardless of what material they're installed in. Zinc or cadmium is basically a sacrificial coating. At least that's how I understand it.