[MPlayer-users] Changing playback speed while movie is playing

[Glin]

Hi,
I found in MPlayer documentation at:
     http://mplayerhq.hu/DOCS/man/en/mplayer.1.html
that changing playback speed while movie is playing is possible, in then 
concrete:
KEYBOARD CONTROL
.................
[ and ]
    Decreases/increases current playback speed by 10%.
{ and }
    Halves/doubles current playback speed.
Backspace
    Reset playback speed to normal.
.................

But when I press these keys, then I get only message(in console) such as:
No bind found for key [

And when I go through mplayer -input cmdlist, I cannot find something
like these commands to set this keybinding manualy.
I have mplayer 1.0_pre5, which is (I believe) the latest release.

Could you help me, please? This is really useful feature for gettin over
boring parts of movies, recorded lectures etc.