Nice vid hehe, ill make it smaller.. link updated.
Ah yes, i do rember that trick from WON now... people would build fac's at the side of there base of pie, do that and put units on the clifs. Very cheaky hehe. Not what i expected, thought u found a way to drive thru them or somthing hehe.
Now that we can edit cell types we can make it not be able to be done, by making all of the clifs impassable.