Hi Dinusha! Yes we have free training videos covering concepts, best-practices, and new product introductions on the entire Aruba portfolio.
You can find the training videos on the Airheads Learning Community here: https://community.arubanetworks.com/t5/Learning/ct-p/learning
We recommend taking the full training courses to adequately prepare for certification, but these videos can be supplementary to help prepare and some of the content is pulled directly from the training courses.
If you have any question, or suggestions for video topics feel free to reach our to airheadslearning@hpe.com