display velocity/speed keyframe for more than one element

Hi !

I'm suprised i can't find the answer by myself, but i need some help here !

I want to display velocity keyframes for ALL my elements in the timeline.

When i select only one element and rightclick on it - i have no problem, option appears (the last one in the menu).

When i select 2 or more, this option dissapears  ! and i can't find the solution in any menu..

I definiltely will not click on each of thousands of elements, so do everybody know the trick ??

thanks!