I know this is an old post but if anyone else sees this here is something that is probably useful:
Here is a comment I put that on the video that tells you how to make it straight rather than require a bend:
After messing around with the blocks for a while, I found a slightly simpler solution. It removes the need of a loop and allows for a straight flow of command blocks. You simply order the command blocks as such: Testor, Setblock stone, Conditional, Testfor air, Unconditional, Setblock air.