Vostfr

[Tanya Shivari]

Stands for Version Originale Sous-Titrée en FRançais which means original version (i.e. not dubbed) with French subtitles.
Often added to video file names.
Sometimes you can also see VOSTFrench, probably to make it clearer for non-Frenchmen.
Just VOST can also be used if its clear that theyre French subtitles (and not for example English subtitles which would be VOSTA: Version Originale Sous-Titrée en Anglais).
In French movie theaters usually only VO (original version) is written to say that the movie isnt dubbed, since its obvious that there are French subtitles. This is opposed to movies in VF (version française, French version) which are dubbed.

[PussyCat]

In many cases means that a video file has been recorded with french sub titles - popular online.