Well, this completely depends on what your business channel is about. Does the unboxing fit the content of your business channel? Will appeal to the same target group? If yes, you can post it there, if not, I would post it to your personal channel.
Also, Youtube won't allow you to upload the same file twice, even if it is on seperate channels. One of the videos could also be seen as stolen content, since the videos will be identical and not everyone knows that both channels are yours.