videos do not work in Impress - LIbre Office 7

Videos do not work in version 7.2 They either show the opening scene but do not play or there is just a grey/white screen and audio wich plays OK.
As I needed this to work urgently, I uninstalled version 7.1 and installed and the videos worked OK.
Can anyone suggest why they might not work in 7.2 ? Many thanks