Jana, Tilasini and others are singing the Mahamantra.
There are many english seminars every year in the different ashrams of Yoga Vidya. You can find them all by clicking here.
You can get the text to the mantra here.
The Hare Krishna mantra, also referred to reverentially as the Maha Mantra ("Great Mantra"), is a 16-word Vaishnava mantra which is mentioned in the Kali-Santarana Upanishad, and which from the 15th century rose to importance in the Bhakti movement following the teachings of Chaitanya Mahaprabhu.