Dear Sebastian, a day (and a sleep) later I found out how to solve the new problems:
I had to delete the config file in ~/.config/vlc manually. The setting Interface>Main Interface>Interface-Modul=Qt-Interface seems to be broken and leads to an unstartable installation until you manually delete the config file. I realized that the graphical problems were no consequence of deinstalling libvdpau-va-gl1. They existed before in Dragon Player as well, I just never tried to fullscreen Dragon Player before and vlc did not play it. Nonetheless these were solved using Video>Ausgabemodule(output modules)>Videoausgabemodul="OpenGL GLX Videoausgabe (XCB)" or "X11-Videoausgabe (XCB)" while the setting OpenGL... in combination with Video>Ausgabemodule>OpenGL>OpenGL-Erweiterung="EGL Erweiterung für OpenGL" is smoother than automatic and a little sharper than X11-Vid... on my computer. A last question I do have: When I understood the package descriptions etc. right then the problems are lying in playing the video over the hardware? How do I find out wether (or which) driver is not working or if this is due to faulty hardware? Thanks alot for your help - I am really relieved right now. Maria
