I was reading an article just this morning about algorithmically created videos for kids that included disturbing and inappropriate content. I'm really inclined to agree here - YouTube is a bad place if you don't know what you are doing or what you're looking for.
I trained my YouTube account so all it does is give me Christian music and related stuff I've approved for work, heh. But I always ignore the trending page (unless there is a new Marvel trailer or NF song lol) and go straight to log in. There's nothing good on that page for nobody.
I think the internet can be used for good, but it's also a minefield of bad videos and communities and you have to be careful what you do with it. With great power comes great responsibility.
666 is the number of a person, i.e. the antichrist. Until it is used in that context, it is simply a number. (Especially given that this is the 666th post in this topic.)
The web is a tool, like a wrench. You can use a wrench to fix a bike, and you can use it to hurt someone. Depends on the user.
May I suggest the guidelines for biblical confrontation in Matthew 18?
My thought is probably that your church is playing the radio while you wait and then calls up a band to play the worship music, is that correct? If that is the case, there's got to be a Christian music station in town for them to play.
Following Matthew 18, you probably need to find the sound-board guy and confront him privately. You may want to take a adult along to avoid being written off. Be prepared for objections, and remind him that playing music like that is dishonoring to God and likely poisoning the young people in the church with bad ideas about relationships.