This video from Derbyshire in England says about itself:
Leisler’s bats emerge from bat box
16 May 2015
In 2008 we erected a bat box carved from a piece of log at one of our schemes. A maternity colony of Leisler’s bats has moved in and in May 2015 we set up a camera and screen so that members could watch them emerge. We recorded the video & uploaded it so you can watch too!
Morphogenesis of the fetal membranes and placentation in the Indian molossid bat, Chaerephon plicata: here.