Roger Corman's campy B movies, children's shows like "Sesame Street" and "Inspector Gadget," and inspirational monologues by celebrities - these are among the offerings on 30 channels that will soon require a paid monthly subscription on YouTube.

Although the world's largest video site has rented and sold movies and TV shows from major studios since late 2008, most people watch videos on YouTube for free. But the Google-owned video site said Thursday that it will ask consumers to pay a monthly subscription for some of the videos on its site.

It's the first time YouTube is introducing all-you-can-watch channels that require a monthly fee. The least expensive of the channels will cost 99 cents a month but the average price is around $2.99.

In the field of paid video content online, YouTube is playing catch up to services like Netflix, Hulu and Amazon, all of which have millions of paying customers.

But with a billion monthly visitors from around the globe, You Tube hopes to quickly add subscribers and add to the money it already makes from online ads.

As is the case with free videos on YouTube, the pay channels will be available for viewing on computers, mobile devices and Internet-connected TVs.

When viewers stumble upon a video requiring payment, they'll get a free preview up to 2 minutes long before being asked to subscribe. Each channel comes with a 14-day free trial, but customers have to enter their credit-card information through Google Wallet if they haven't yet.

Several channels offer discounts on the monthly fee with an annual subscription.