Born on March 13, 1963 in Narva. His real surname is Menshikh. From the age of 4 he played in the puppet theater of the local Palace of Pioneers. Then he played in the People's Theater under the direction of Yuri Mikhalev (now the Ilmarine theater). In 1984 he graduated from LGITMiK (class of Z.Ya. Korogodsky). He played at the Leningrad Youth Theater, and from 1999 to 2003 in the troupe of the Small Drama Theater. Since 1987 he has been experimenting in various theater companies, traveling a lot, meeting with representatives of various experimental movements, attending theater seminars and conferences, and participating in various international festivals; since 2001 he has been actively teaching.

From 2004 to January 2011 he hosted the "Frankie Show" on the radio station "Silver Rain", in which he managed to play 316 characters. The main character of the animated web series "Mr. Freeman" speaks with Demchog's voice. Author of the books "Self-Liberating Game" (2004) and "Playing in the Void" (2009-2012). Candidate of Psychological Sciences.