Crawl with elytra in one block high spaces

There is a very big mistake in this new version because I want it fixed by a elytra you can transfer blocks minecraft and can walk only one block up and also you can go under the blocks
WATCH THIS VIDEO FOR MORE INFO
https://www.google.es/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0ahUKEwjFkeitz_DKAhXL6xQKHXQeDzUQtwIIMjAF&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DLIjKsoq3BAQ&usg=AFQjCNHMUJlEVyDcGwzO2Boi3nF0GhiVUA