Well, the "Church" you are referring to is just a building, there is nothing special about it. It's just a place where people of a mutual religion gather to learn and worship. Many activities not directly related to religion happen in churches. For example, my church lets two different homeschool programs use the facilities. We also host various concerts in the main hall. In addition to that, we have airsoft games in the building monday nights. So I find nothing wrong with the youth group, or whatever group it may have been, using the facility to watch the game, it's fellowship.
