Good question, it depends how the NFL rules the play but a Fumble Recovery is awarded to players who recover a fumble in the play's description. So for instance if you give points to a RB for a fumble recovery and Alex Smith fumbled a snap and Jamaal Charles recovered, he would get a point for a fumble recovery not an opponent's fumble. If the NFL rules a defensive player recovers a fumble on a complicated play, they may award that player with a fumble recovery as an IDP player in your instance, but likely since possessions never changed in your example, that wouldn't even be a FR for the DB (again it would depend how the NFL rules the play and if they award a FR on a change of possession -- if so, opponent fumble recovery would only take)

Basically it's separating the issue of having offensive players being credited with their own fumble recoveries or recoveries from their own team's fumbles like the Chiefs' example. If you just wanted opposing fumble recoveries from other teams recorded, you can select the opposing fumble recovered category. It's something I wouldn't worry about if you're just giving FR points to IDP's.