Question about Crash Course part 1

I noticed today that in measure 6 of Kuroishi Yosare Bushi (when played with “authentic timing”), Kyle plays note 1 (ni-no-ito, position 4) and then kind of waits with san-no-ito pressed down and then slides off of it for note 2 (san-no-ito, open string). This occurs at about 19 seconds into this video: https://bachido.com/school/crash-course-1/chapter-16

Just curious if this is a specific technique or just a little trick of the trade.

Hey there,

It’s a technique for lengthening the duration of a note. We call it ゆり, but it’s really just a variation of すり without moving off the note.

You might also see it referred to as vibrato.

Here’s Reigen talking about it in depth.