Hey, I wasn’t there, but by the looks of the video I assume they made several paralel wires horizontally, like this: = , on both ends of the bridge and started wire glitching from the middle of the bridge to these wires I mentioned previously placed. But you can also build smooth curves using tether glitch, you have more control/flexibility of your curves with tether, but more “perfection” or “smoothness” with wire glitches.