Everything you need to know about the Korean War can be found at The War Memorial of Korea in Yongsan-gu. These include daily screenings of war themed Korean films such as the Northern Limit Line (2015), Roaring Currents (2014) and Assasination (2015). The cinema itself is actually up to par with any normal movie theater in Seoul but is free of charge.
Before the screening begins, a curator of the museum will point out the exhibition that is related to the movie you will be watching, allowing you to get more historical information about the film. The museum will be closed on Mondays (if a public holiday is on a Monday, Tuesdays will be closed), but from 2pm on all other days, the first 100 people will have access to the cinema. A special exhibition of the Turkish army during the Korean War will be on display, and it will surely be a worthwhile visit.