Blue tit first egg!

Here is a video and photos today, sorry about quality as having to take photos from TV, looks to be 8 chicks with one unhatched egg so far, dad is regularly coming in which is a good sign but did see a strange blue tit at the box today only knew it wasn't dad as mum was very agitated at it's presence so can only assume it is another female.
drive.google.com/file/d/1u1uIyA1caKE-bNoOA7dX0LL2QoNScMu4/view?usp=sharing