Postby Esquilax » 12 Jun 2021 02:35
The only way I've found to achieve what you are describing is to disable auto-playback of new items in the Interface Preferences (click Show All to reveal), and from then on launch VLC first, then double-click (or drag/drop) the mp4 file(s) to add them to a playlist. Double-clicking mp4 files to launch VLC always auto-plays.
I too would prefer it if VLC didn't automatically start playing, but I think that's how it's always been.