Can't see your video for some reason, but the drawbridge is a weird "block". This is how it worked in A18:
1) Provide support blocks for the middle of the drawbridge span
2) Place drawbridge
3) Add blocks at the hinge end of the drawbridge (if it's not already abutting the edge of your base)
4) Remove middle supports
You'd think you could just snap the hinge end to, say, the wall of your base, but it needs to be resting on something in order to be placed. It'll still "stick" to the wall, you just can't snap to it for initial placement.
It's weird.