If I understand this play correctly, 10 players broke a huddle, then got set in their formation (i.e. no one moving). Then A35 enters from the sideline, gets between the numbers and remains in motion until the ball is snapped.
Fellas, this is a legal play.
If any of the original 10 were still moving when he entered the field, then yes, we have an illegal shift; however, a shift requires TWO players, not one. Therefore, A35 is under no obligation to get set.