The VideoLAN Forums

Problem solved.
After uninstalling vlc-2.1.5-win64 and reinstalling vlc-2.2.1-win32 the effect vanished.
Apparently the 64 bits version contained bugs, and I could not retrieve anymore the 64 bits version on the Web.

All videos play with a coloured bar in the center (red, brown, green; scale 0-60)
Windows 10 64bits
VLC version 2.1.5
No idea what is the cause