Hi there! Fairly new KDE user here.
I have some problems opening samba shares on my network: when I try to open a file on a samba share it doesn't Just Work. For example, if I open a video with SMPlayer or VLC it sais it can't open the file "smb:/path/to/file/". If I open a text file with Calligra Words, it gives the same error, but it works fine with Kate.
I didn't have this problem with gvfs based applications. The difference is, gvfs mounts the samba share locally and passes a local path to the application, while Dolphin passes a smb:// URI to the app, which doesn't work.
I do have the following line in vlc.desktop file

X-KDE-Protocols=ftp,http,https,mms,rtmp,rtsp,sftp,smb

I'm using KDE 4.9 on Arch Linux. File browser is Dolphin. Tried Konqueror too, but no luck.

The error message given by Calligra is very unusual - it is a KDE application and therefore should support KIO.
Not sure about SMPlayer, but VLC should also support smb:// assuming it's plugin for that protocol is installed. It might be worth running a search in your package manager here.

The issue with KDE opening files due to the non-use of local mounts is known unfortunately.