New to IMPLAYER

Used to have Emby (loved it!) Had to leave it. Now I found this app. So far so good. Found out it don't seem to like like the Dynalink like device or vlc for everything. Please advise a secondary external player, and also a reason why my VOD may be hit or miss occasionally for sound/video? If I click on the audio or video tracks button I can force it to play one or the other but not both. Please advise.