[Tracker] tracker doesn't find video files

[gebi <gebi fastmail fm>]

strange:

gebi kepler:~/Desktop$ tracker-search feynman horizon
/home/gebi/work/literatur/mechanics/berry.pdf
/home/gebi/work/literatur/relativity/enery-momentum_all_relativity.pdf
/home/gebi/Desktop/Horizon 1981 Feynman - The pleasure of finding things
out.avi

finds the avi video (see last line)
but explicitly searching for the feynman video :

gebi kepler:~/Desktop$ tracker-search -s Videos feynman horizon
gebi kepler:~/Desktop$ 

gives not results ?