Use of multimedia services has become very important in learning process. This is due to the traditional approach of document based assignments not provide any feature which allows to evaluate some basic competences (oral communications skill, for example). In this paper, the UNED (Spanish University for Distance Education) solution will be presented focusing on user's interaction: lecturers and students. In the first case, the lecturer has to define a task and propose a solution (available only at the end of task availability). This solution is also video/audio based, so the student can learn about it and compare it with his/her solution. The student has several attempts, in order to try better responses and decides which of these attempts will be selected as final response. The whole interaction schema will be presented and how is integrated in the e-learning platform as a usual task (like document based tasks). This integration permits the use of all features of the platform evaluation tool, simplifying the evaluation process and tasks grading (no special procedures are required).