This song can be useful when you are about to hoist your child. They may have started to prepare themselves for the movement, as they have recognised their sling is being placed around them, but hearing the song will tell them that they are about to be moved (and therefore minimise any anxiety they might be feeling.)
You’ll also notice the onbody signs for “up” and “down” at the end of the video. Your child will be familiar with these signs, so do use them at home – they will also help your child understand and feel more comfortable with what is happening.