See below for a guide on how to get all of the collectables on the Streets of Hogsmeade level:
Professor Snape (CHARACTER):
In the area in the street once you are swamped with enemies, after being prompted to use the Protego spell, there is this collectable in the building with the two enemies upstairs, but it is only unlockable having earned the Apparate spell, later in the game. You need to use this spell to get over the barrels blocking the way into the building (video time: 02:47).
Death Eater (CHARACTER):
After the street fighting and once you get the instruction to get to Honeydukes, ignore the objective indicator and go down the alley between two buildings to the left of this indicator (video time: 01:40).
Wandering Part 2 - Determination (MUSIC):
While Hermione is unlocking a gate for you, head to her left to get the collectable from around a corner (video time: 02:01).
Challenge 2 - The Streets of Hogsmeade (CHALLENGE):
After going through Hermioneâs gate, there is a collectable on the right, as Ron states that the level is nearly over (video time: 02:27).