You can try searching for "Shanmuga Kavasam by Seergali Govindarajan" on websites that offer Tamil devotional music downloads. Some popular options include music streaming platforms like Gaana, Saavn, and YouTube.
I have heard it is with the same tune of kantha sasti kavasam. no commercial dvds available. you can hear the song at audioboo.fm/boos/587786-anantha-sakthi-kavasam-audio-mp3 and at ananthasakthikavasam.podomatic.com/entry/2011-12-13T21_16_42-08_00 and see it at youtube.com/watch?v=1LFLQtQGlK8