Thanks for the video. I have a 2014 ST-S that I am going to be doing my first brake pad change on this weekend. I figure they are all pretty close, so it is good to see how it is done, at least on the F3.
Sorry for the late response. I would say the 2 most common things that can kick a brake failure light is low brake fluid or the brake fluid level sensor is bad.
I would recommend to get proper buffing pads and do the rotors where it sits on the hubs.... both sides hubs and inside rims. Light buffing, just enough to polish