A great addition to the MCAT practice passages for each of the four MCAT sections would be a brief summary at the end of each quickly directing students to videos on topics they struggled with. 

I've observed at time the explanations are unrelated to any content within the Khan Academy universe, and it might be better for the student and for the future usage of this resource to hyperlink videos or documents within the explanation. 

For example, if a passage covered causes, symptoms, and prevalence of schizophrenia, and a student missed a majority of passage questions--it would be awesome to have a hyperlink from the relevant series to automatically populate and suggest additional review upon completion of all questions. 

"It seems you are struggling with topics x, y, and z, have you watched these videos on those topics?" 

This wouldn't help much with questions requiring information directly from the passage, but it might help some students better if the given explanation is short or confusing. 

Thanks for all the free resources, learners all over the world appreciate it!