Corsa Start Up Noise/Rattle

Hello, I have a 2008 (58 reg) Vauxhall Corsa SXI 1.2 16v and when i start it, there is a loud rattling sound coming from the drivers side and it seems to quieten down/dissapear after a couple of seconds. I have a video of the car starting up and what’s going on under the bonnet here (the second part of the clip is the running sound after a couple of seconds, not sure if its how corsa’s normally sound when running or if i should be worried): https://streamable.com/mt6ao
Does anyone know what the issue could be or what the black box is called (the one that shakes and seems be where the rattling is originating from)?
Thanks!