This has yet to be implemented to all youtube partners but inevitability it will. Only a selected few have this "pay-to-watch" feature.
Sense many people here have/want to start a channel it'd only be appropriate of me to share this information to give you a head start.
Here are some coverage on the topic:
Just google "youtube pay-to-watch" or whatever.
P.S I'm sure Matty all ready knows aaaaaall about this ;)
(If this all ready has been posted then I ask the mods to please remove this)