Hey mhamidir,
The video component is conceived to be very difficult and challenging but in reality it is not. You will be able to practice both the video and the written components and get the feel of the process once you start the essay. Personally, I feel that you can never be completely prepared for an impromptu speaking exercise. However, practicing and going over some questions will be helpful. You can find several resources online on what type of questions will be asked - one would be behavioral and the other an experiential type. Be aware of all yourself - your strengths, weaknesses, hobbies, interests, likes/dislikes, favorites, personal and professional experiences, learnings, etc., and you should be able to cover a good number of questions. Also, if you are not comfortable speaking in front of a camera, you should start working on it since people usually focus on their laptop screens and not the camera. So, practice till you are confident and just go ahead with it. Oh, and try and enjoy it. It is quite an experience
All the best!!