Enrollment, tuition and other fees collected from students enrolled in graduate level extension, and graduate level off- campus, courses for credit taught off the campus of the university, excluding educational television courses, shall be paid into a special fund and be used for the purpose of partially or fully covering the costs related to the development and teaching of such graduate level courses: Provided, That no portion of such fees committed to the retirement of any revenue bonds heretofore issued pursuant to the provisions of articles eleven-a and eleven-b of this chapter shall be paid into such special fund for so long as any such bonds remain outstanding and unpaid.