The girl in the video has a lot of repetitions and her speech blocks are silent. For example, other stutterers prolong sounds like llllll-lllllll-laté. But she makes it silent which is an additional condition - an additional part of avoidance that negates 'don't hold back'. As I understand, there are 2 behavioral ways to create a speech block: One way is to stop breathing out. The second way is to stop moving your mouth (like tongue and jaw). The girl in the video does the second way, whereby she stops moving her tongue or jaw to the next position in her mouth to form the next sound - especially the back part of her tongue that we can't see, stops with moving.