Do you know much about YOuTube and all the videos and vlogs that are on there?
I know about Youtube in general. It was created by three former Paypal employees, Chad Hurley, Steve Chen, and Jawed Karim in 2005
My daughter keeps saying she wants a  YouTube channel of her own - not sure if I should let her.  Do you have any advice on that - she's 16.
Well, Youtube allows people to upload, view, rate, and share videos as wel las subscribe to others 'channels' so if she can make interesting content she should be fine. Also, she could become popular and get rich lol
LOL wouldn't that be nice!  But can predators contact her through it?
Sure, but they can do that through any medium. Snapchat, Facebook, etc. Youtube offers a wide variety of user generated videos. Not all are appropriate 
that is very true.  So many things to keep an eye on these days.  Does it cost anything to be a Youtuber?
Nope. It's completely free. It's worth nothing, however, for your previous question that videos can be flagged to not be shown to those registered as under 18.
I guess they could just make up an age and say they are 18
That's pretty much what everyone does. It's certainly what I did back then lol.