@Alchemix:
Thanks very much. Your post of the two error lines that you didn’t get led me to a new google search with just those two lines. This helped me to solve the problem.
The search led me to a link in an Arch-Linux forum.
Although the problem described there seems not the same exactly, the solution worked for me just fine: I opened the dialogue
preferences > video > output
and tried various entries.
Finally, setting the value of “output” from the value “Automatisch” to “XVideoausgabe (XCB)” worked just fine. Audio and Video are both perfect. I also tried the scene selection and it worked as well.
So, thanks again for your support.
A short postscript:
Ironically, the error list of the terminal ist longer now (though changed, of course) 
Just for fun: here it is:
[carsten@carsten-pc ~]$ vlc dvd:///dev/sr0
VLC media player 3.0.11.1 Vetinari (revision 3.0.11.1-0-g52483f3ca2)
[000055da46124660] main libvlc: VLC wird mit dem Standard-Interface ausgeführt. Benutzen Sie ‘cvlc’, um VLC ohne Interface zu verwenden.
[00007fa444001120] dvdnav demux: DVD Title: SPECTRE
[00007fa444001120] dvdnav demux: DVD Serial Number: 47981b54
[00007fa444001120] dvdnav demux: DVD Title (Alternative):
[00007fa444001120] dvdnav demux: DVD disk reports itself with Region mask 0x00fd0000. Regions: 02
[00007fa444001120] dvdnav demux: Attempting to retrieve all CSS keys
[00007fa444001120] dvdnav demux: This can take a long time, please be patient
[000055da4622de70] main audio output error: too low audio sample frequency (0)
[00007fa4441d2670] main decoder error: failed to create audio output
[000055da4622de70] vlcpulse audio output error: digital pass-through stream connection failure: Nicht unterstützt
[000055da4622de70] main audio output error: module not functional
[00007fa4441d2670] main decoder error: failed to create audio output
[00007fa44000c600] main video output error: video output creation failed
[00007fa44406e400] main decoder error: failed to create video output
[00007fa4400599f0] main video output error: video output creation failed
[00007fa44406e400] main decoder error: failed to create video output