ALL my rifles, from my 50s Remington 722 to my AR are single stage. I need a lighter trigger in the AR. Most are set for 3 lbs. Two stage triggers are usually on old milsurps and people buy timney or whatever single stage triggers to replace them. I don't know why ANYONE would prefer a 2 stage trigger. I have some on milsurps, but they're collectible and I rarely shoot them and don't use 'em for anything important.
I've never ever seen a non-mil surp with a 2 stage trigger from the factory. More accurate? Do tell. Is that why nobody shoots bench rest with a mil surp trigger? :rofl:Two stage triggers are generally more accurate than single stage.
Most guns are two stage, the AR is an exception, I'm sure there are others.
The video in the op doesn't explain the difference between the two very well. Simplified, a single stage trigger has no pretravel before releasing the firing pin/hammer where a two stage, there will be some distance of take-up before the firing pin/hammer is released.
The single stage (generally) will be shorter travel than a two stage... faster for 3 gun and such. A two stage will be a longer pull, but allows for much better control... long range and precision shooting. Both can be heavy or light, the style doesn't really effect the poundage or crispness of the break.