Oh, its simple. Youtube allows us to upload videos and share it with our friends or anyone on the internet. Say, you could capture a session from your church and broadcast it to those who missed the service.
This costs a lot of bandwidth and storage space to the service provider (YouTube).
YouTube is for anyone and hence there are a lot of videos on their site thats not appropriate to the christian community. Thats why I'd love to see a christian alternative to YouTube.