In this video Concentric Mate has been used to align nut and bolt. After that this Concentric Mate has been supressed to create a Mechanical Screw Mate between Nut & Bolt.

These two mates are not in conflict with each other therefore no need to suppress. Non supressed Concentric Mate along with Mechanical Screw Mate is not giving any problem to me.

Why is Concentric Mate suppressed in the video?

SolidWorks Tutorial # 269: updated Bolt and nut (new thread feature) - YouTube

Time 13.08-14.00