What is the ruling on selling satellite dish cables and connectors, given that their predominant use is for watching movies, TV series, and music videos, and (what about) computer connectors? And is the ruling on selling to a Christian's home the same as the ruling on selling to a church?

It is not permissible to sell satellite dish connections and similar items that are predominantly expected to be used for unlawful purposes, because means are subject to the same rulings as their ends. Whatever leads to something unlawful is itself unlawful, like selling weapons to someone who will use them to kill. However, there is no harm in selling items that are not predominantly expected to be used for unlawful purposes. Similarly, it is not permissible to sell tools for building churches, so as not to cooperate in sin. As for dealing with Christians in permissible matters, there is no harm in it.