This was part of a chain of 3 independent cinemas in Siam Square. One was torched during the riots of 2010. The remaining two seem to be struggling for identity. Sometimes being inventive and unique in what they show, sometimes apparently following the crowd.
Check movieseer.com for shows and times of "all" cinemas, and see if this place is running anything unique.
On the menu to the left, pick Bangkok. On the next menu, pick Apex:Lido to see shows
Or this site: http://www.apexsiam-square.com/home.asp
Even if not - the place has a character of Bangkok cinemas of a few decades ago - so may still be worth a visit!