Video readings on Purple Ocean last from 2.5 to 3 minutes and they are $10 and delivered to your account within 24 hours. If you want a rush reading, you need to look for an advisor that offers them (noted by the green figure of a person running on their profile). Rush delivery orders are delivered to your account within 1 hour or you may cancel and get your credits back. They are $15, and also last from 2.5 to 3 minutes.
Live video calls are offered by advisors who the blue video camera on their profiles. Live video calls can last as long as you want, and each advisor charges their own per minute rate, whatever that may be. Those details can be found on each advisor's profile page.