Reading that you are not able to Timeline Scrub in VV4, got me to ask,
How do you move around the timeline and view areas of the video and clips, if you are not able to use your mouse to click on a spot and move around to view the video?
Place your marker on the timeline start playback by hitting spacebar or play on the timeline then press L-scrub forward J-Scrub backwards and K-Stop to scrub through the timeline.
You can also use the "Rate" slider on the left hand side center of the screen to scrub as well.
You can slo edit the rate of the scrub in the preferences under the "Editing" tab
It's not really a True Scrub, but it will work for most things
if you are not able to use your mouse to click on a spot and move around to view the video?
You CAN use the mouse to move around and view the video. Just click in any blank area and drag. I usually click above the timeline. It WILL create a selection area, though.