A "Lesson" is a collection of interactive quizzes for a single video. Everything is free and free access.
There are 3 interviews in this clip. You will see the words "Present Perfect" flashing on the screen when the present perfect is used. Your job as student is to identify the words which make up this tense!
There is also review of structures covered in previous lessons.
Real English English as a Second Language: Videos for Students and Teachers
Finally, you will find exercises for all these videos on real-english.com