OPA211: Question about Vib calculating in Precision Lab Video

Part Number:OPA211

Hi there, 

I am learning Precision Lab Video, and found one equation which is not inconsistent in different lectures.

(1) In lecture 2.1,Vos and Ib - slides, page 16(as below), Vib is well explained to be Vib=Rf*Ib. And I believe this is correct.

(2)However, in lecture 2.2, Vos and Ib - Lab - slides(as below), page 22, Vib is described as Vib=Req*Ib=(R1//Rf)*Ib.

I am confused why these two equations are different? Did I miss something? I think these two circuits should be the same, just a simple amplifying circuit. Thanks.