So I was trying the new enchantment where you move faster while sneaking. I used the maximum enchanting level of it on my pants and then I bridged across a lava lake. Suddenly I noticed that I place blocks somewhere even though I'm just looking at the same block. Whenever I moved it build the block that was in my hand upwards or downwards. It depends where yoh place the first one. It's easy to understand if you watch the video. In the beginning I look at the block while holding rightclick. When I place a block on the block in front of me it will continue building on this block if I move. Don't try do understand it trough the text. Just watch the video if you want to understand