Hi, apologies for probably posting this in the wrong place…
There has been a regression for quite a while with nvidia proprietary drivers v525, that breaks va-api - that is: vlc segfaults and does not work anymore 
You may also see errors like this:
glconv_vaapi_x11 gl error: vaInitialize: unknown libva error
If you have a hybrid setup, then you should be fine with using/falling back to libva-intel-driver, and that’s probably why you did not realise that there’s been an issue…
But if you have just the nvidia card only, then you must install libva-nvidia-driver from the AUR - NOT libva-vdpau-driver, that’s the one that does not work anymore!
More info here:
https://aur.archlinux.org/packages/libva-nvidia-driver
https://bbs.archlinux.org/viewtopic.php?id=282638