How to enable seekbar?

If you mean force it to appear programmatically, no. You could potentially send a Play/Pause twice via ECP, but I don't know if that would execute fast enough to avoid an actual pause.

I don't see a seekbar at all for pause or ff. Is there something special I need to do.

Oh.. roVideoPlayer, not roVideoScreen. roVideoPlayer is strictly video playback. Any overlays, like the seekbar, would need to be custom drawn with an roImageCanvas (see the customervideoplayer example). If you want that functionality built in, you should use roVideoScreen instead.