I want to share with everyone the video explanations to all of the problems in the quantitative section of the Official GMAT Quantitative Review 1st Edition(Green supplement book). http://www.gmatquantum.com/og2-1stedition/
This is for students who may only possess the 1st edition of the Official GMAT Quantitative Review. You will also find the explanations to the Official GMAT Quantitative Review 2nd Edition as well.http://www.gmatquantum.com/og2main/
I have also listed the overlap between the two guides for students who have both of these guides.
Comprehensive GMAT Quantitative Course: GMATQuantum
Free Video Explanations: OFFICIAL GUIDE GMAT 13, 12, 11, 10; QUANT REVIEW 2nd, 1st.