Catalyzes the dehydrogenation of methylene-H(4)MPT. 5,10-methylenetetrahydromethanopterin + NAD(+) = 5,10-methenyl-5,6,7,8-tetrahydromethanopterin + NADH 5,10-methylenetetrahydromethanopterin + NADP(+) = 5,10-methenyl-5,6,7,8-tetrahydromethanopterin + NADPH Optimum pH is 6.0. Optimum temperature is 35-40 degrees Celsius. One-carbon metabolism; formaldehyde degradation; formate from formaldehyde (H(4)MPT route): step 2/5. Homohexamer. To M.extorquens MtdA.