The -add-to-playlist option doesn't seem to work -- it just keeps launching new instances. I'm trying to externally control SMPlayer but, without this option, it doesn't seem possible because I'm not aware of any action that lets you change the video file or URL. Also, I need to maintain the multiple instances option on this system (which I assume is why -add-to-playlist exists in the first place, otherwise calling SMPlayer with another file/URL would just run in the existing instance).
Any help would be appreciated.