Thank you both for your continued help.
Raoul : I was sure I'd checked previously, but you're right - the oszl(ite) option is in 2.4.6. I'll start using it ASAP.
JohnM : I assume the .osj file is in the top level of osz ZIP file. I opened it in NotePad (is anything else better ?)
Here's an extract of the first few lines ...
[{"openlp_core": {"lite-service": false, "service-theme": "Bluenote V3"}}, {"serviceitem": {"header": {"processor": "VLC", "search": "", "audit": "", "data": "", "capabilities": [12, 16, 17, 4], "footer": [], "theme": -1, "notes": "", "xml_version": null, "type": 3, "from_plugin": false, "icon": ":/plugins/plugin_media.png", "name": "media", "end_time": 0, "background_audio": [], "timed_slide_interval": 0, "auto_play_slides_loop": false, "auto_play_slides_once": false, "theme_overwritten": false, "media_length": 190, "plugin": "media", "start_time": 0, "will_auto_start": true, "title": "Greatest Day In History (Acapella).MP4"}, "data": [{"display_title": null, "image": ":/media/slidecontroller_multimedia.png", "notes": null, "path": "C:\\Users\\catherine\\AppData\\Roaming\\openlp\\data\\servicemanager", "title": "Greatest Day In History (Acapella).MP4"}]}}, {"serviceitem": {"header": {"processor": null, "search": "", "audit": "", "data": "", "capabilities": [2, 1, 5, 13, 8], "footer": ["Easter : The Easter Shout "], "theme": null, "notes": "", "xml_version": null, "type": 1, "from_plugin": false, "icon": ":/plugins/plugin_custom.png", "name": "custom", "end_time": 0, "background_audio": [], "timed_slide_interval": 0, "auto_play_slides_loop": false, "auto_play_slides_once": false, "theme_overwritten": false, "media_length": 0, "plugin": "custom", "start_time": 0, "will_auto_start": false, "title": "Easter : The Easter Shout"}, "data": [{"raw_slide": "{it}{center}The Easter Shout{/center}{/it}\nAllelulia. Christ is risen!\n{y}{st}He is risen indeed! \nAlleluia, alleluia, alleluia.{/st}{/y}", "verseTag": null, "title": "{it}{center}The Easter Shout{/"}, {"raw_slide": "This is the day that the Lord has made:\n{y}{st}let us rejoice and be glad in it.{/st}{/y}\nThis is the day that the Lord has risen:\n{y}{st}let us rejoice and celebrate.{/st}{/y}\n", "verseTag": null, "title": "This is the day that the Lord "}]}},
I can see the file is made up of 'serviceitem's . The video name seems to appears twice within a single serviceitem ? Do I just delete the whole serviceitem - i.e. from the start of the one with the video all the way to the start of the next ? Or might there be be any embedding or recursion that might confuse things ?