example:
$ffplay -f dshow -i video=screen-capture-recorder -vf “drawtext=fontfile=subfont.ttf:text=%m/%d”
You can use these abbreviations:
http://msdn.microsoft.com/en-us/library/fe06s4ak(v=vs.71).aspx
ref: http://einar.slaskete.net/2011/09/05/adding-time-stamp-overlay-to-video-stream-using-ffmpeg/