Harry, Mahashakti and Heidi are chanting the mantra Om Namah Shivaya. This is one of the most popular mantras. Shiva is the "destroyer of evil and the transformer" within the Trimurti, the Hindu trinity that includes Brahma and Vishnu.
You can be a part of the daily satsang in one of the Yoga Vidya ashrams if you visit us. We also do have many Bhakti seminars in english, for example: "Bhakti Yoga with Swami Gurusharanananda" click here for more information about our english seminars.