I realize that it's already quite late there in London, and that you might have had a few ales - but your thread title bears no relation to the question. ie "Vertical Zoom", "Vertical Scroll".
So here's both answers which you can peruse in the morning after it's all worn off:
1. Vertical Zoom Audio on all audio tracks Option
plus Command
plus [ or ]
2. Scroll Vertically using Page Up & Down buttons on an extended keyboard. or drag the darker elongated bar (no, not that pub in Soho)
or better yet, buy yourself a
Kensington Expert Wired Trackball and use the scrollwheel to continuously scroll with one hand while supping London Pride with the other.
"scrolling". What a wonderful word. It conjures up images of other activities.
Judge: "Will the defendant please rise. You stand accused of gross, indecent scrolling. How do you plead?".
Pro Tools User: "Guilty, your honor - with extenuating circumstances".
for more shortcut tips, check out this awesomely useful website (go to the zoom section at the side panel):
http://www.protoolskeyboardshortcuts...ard-shortcuts/