osso-media-server is the internal media player engine (gstreamer), hence less skipping because it uses the GPU. i've found that the moment the media player fails to play a file (for whatever reason; actual unsupported format or due to it trying to cache video thumbs) all subsequent attempts will result in failure.

however, if i use osso-media-server via kmplayer to play an unsupported file (and failing obviously) i can still select a supported file and it will play fine.

beginning to think that it's something to do with the gui for mediaplayer itself and not the gstreamer component, as [can't remember who] showed an error log saying that it was caused by qtdemux.