Catalyzes the transfer of a methyl group from dimethylamine to the corrinoid cofactor of MtbC (By similarity). No evidence for expression of this protein has been found after growth under presumably inducing conditions (PubMed:16096277). Co(I)-[dimethylamine-specific corrinoid protein] + dimethylamine + H(+) = methyl-Co(III)-[dimethylamine-specific corrinoid protein] + methylamine One-carbon metabolism; methanogenesis from dimethylamine. Belongs to the dimethylamine methyltransferase family.