Search for user videos using terms such as CHURCH and SERMONS. They are plenty of them.
The only issue might be parishners who object to having their likeness published worldwide on YouTube. They could file to have the video with their image removed.
I'm no lawer ... but posting a sign may give you some protection. Unfortunately, if someone files such a claim, you cannot dispute it, even if you have a signed contract stating you have their permission. The process does not include an option to appeal.