@Patches,
Anyone who signs up for a youtube channel can sign up for a partnership, through which you can monetize your videos and get ad revenue for every person who see's the ads associated with your channel. the highest youtube earner made $7m in 2012. that's Ad revenue alone, not including sponsors and product placement.
When people monetize a video talking about spiritual experiences, it goes against the grain for me, it is exploitation of faith, and doesn't sound like a very christian thing to do