Comment 6 for bug 207334

I don't know if this is a bug.

The version of mplayer included in ubuntu just simply doesn't have the scaletempo filter, it was added some weeks after 1.0rc2 was released.

On the other hand smplayer is ready to use that filter (but I think it won't try to use it by default). I think it's not a bug to be ready for new features. Also the help in the preferences dialog already states that that option requires at least mplayer dev-SVN-r24924.