Hard one to call. The breastband lacks a definite downcurved edge, and bird doesn't seem quite dark enough. Likelihood of Leaden is just generally higher. Greame Chapman's notes on differentiating Leaden from satin mentions the undertail shafts which is quite noticeable in this photo "Leaden Flycatcher males have a grey undertail with clear white feather shafts - male Satin Flycatchers have a plain, dark brown undertail in which the feather shafts are not noticeable." (http://www.graemechapman.com.au/library/viewphotos.php?c=181&pg=1)
Given Ryu's comments on under tail I am happy to go with Leaden. I note also that Menkhorst et al p455 show a light grey undertail for Leaden and a blackish undertail for Satin.