I know, you posted a link.
but if you compare some date/time stamps, we’re nearly six years past the initial point of contact.
So apparently they have no intention to change that, and I can understand it.
But discussing it here will have even less effect then. 
Dragon Player, despite being an official KDE application, would not stream over samba on multiple distributions (openSUSE, Manjaro, Kubuntu come to mind).
Yeah, right.
The corresponding line is apparently missing in dragonplayer’s .desktop file.
TBH, I don’t use Dragonplayer and never really used it.
With Kaffeine (another KDE media player, and installed as default media player upto 13.2) this works fine though.
I heard some reports that altering VLC’s desktop files would help, though in my case it proved to be somewhat inconsistent.
openSUSE’s VLC .desktop file does specify that VLC supports smb://, no change needed.
It actually contains this line already:
X-KDE-Protocols=ftp,http,https,mms,rtmp,rtsp,sftp,smb
I had better luck adding the samba credentials into the VLC >> preferences >> advanced >> smb module field.
That’s unrelated.
It doesn’t change the way dolphin (or KIO) opens VLC.
As VLC does support smb:// natively (and doesn’t use KIO, KIO/dolphin just pass the URL), you need to specify the credentials to VLC though, yes.
Thanks for the information about KIO. I understand better what exactly it does in the background now. I just feel a local mount point solution is a bit more straight forward. I mean, that’s what happens when you mount manually in terminal, so it mounting in a similar fashion via the interface fits.
It’s more straight-forward for (non-KDE) applications that only support normal files, yes, but would only work for SMB (and some few selected other protocols maybe).
But KDE does have its KIO anyway (since years, at least KDE3, maybe even earlier), which is much more flexible (it supports plugins for new “protocols”, the kio-slaves), and is being used by all KDE applications.