downloaded via coursera-dl

$ pip install coursera-dl

$ coursera-dl -u youremail -p yourcourserapassword course_name -f "pdf" --path=here/is/path/to_folder course_name

to extract all pdfs from all folders recursively

$ find here/is/path/to_folder -iname "*.pdf" -exec mv {} here/is/path/to_folder ;

delete all empty folders

$ find here/is/path/to_folder -type d -empty -delete