Random Crawling Mode If Against Block

If you are standing next to a wall where the bottom block is missing, if you go against the block, it will randomly put you into crawling mode. I discovered this while strip mining. Attaching video where I got it to happen once, I had to try and get it to work. Sometimes it will just happen for no reason without the crazy mouse movement. https://www.youtube.com/watch?v=1K5mGoYu6aY