The video shows:
If a player (with soul speed enchantment boots) crawls in the space of 1 block above the sand of souls, then the speed effect will appear. But if the player crawls in such a de space above the soil of souls, then he will not have a speed effect, although he should appear.
Confirmed, some crawling has faster in Java Edition
[media]For Bedrock The soul soil does not work except soul sand works
Create a setup with 5-10 blocks of soul sand or soul soil
Create 5-10 blocks for top of crawling space
Add trapdoors to start to end of top blocks
Open and close to crawl it then move forward
Observed result: ❌ The soul soil will not work