Blue Tits - Orpington

I I’ve had a blue tit show a lot of interest in a next box. Have seen her taking items into the box (unfortunately I don’t have an internal camera). 

she’s been a little quieter lately, I have seen her take feathers and cotton into the box which I’m sure is at the later stages of nesting. 

The video attached shows her today, I’m almost certain I can hear babies but would she be feeding them from outside of the box? Have a look and let me know what you think she’s up to. 

youtube.com/.../gHYCa0EVc-8