The seeking bar very much depends on the skin you're using! Perhaps try a different skin. There is an excellent collection of skins on
goety's site (item 6 if you press on
Help to Help hereunder). In fact most skins display either time (elapsed and total) or the number of the frame (toggle between the two types of display by clicking on it) so that you can exactly (in time or by framenumber) position the slider where you e.g. wish to start the movie.
Further, BSPlayer already has different playback-speeds. Right-click on movie window and select "Playback rate" (1/2x, 1x, 2x and increase/decrease by 10%
(the last two options also accessible using key F5 or F6)).