To view videos on this Site, we'll call Vsite, visitors select a link to paypal, from Vsite, to pay for credits. The credits are added to their Vsite account. They use the credits to view videos at Vsite. All payment transactions take place at paypal. Does Vsite need an SSL certificate? Or is that overkill? I'm not sure what the benefit would be to have an SSL certificate in this case. I look forward to being enlightened.
I don't think a SSL certificate is necessary in this case, necessary being the key word here. Paypal has it's own SSL certificate and that's where the payment takes place. As long as they aren't entering sensitive information on a webpage belonging to you, you don't need an SSL certificate.
Since you mentioned that all the payments take place on the paypal website than you do not need and SSl certificate. But for future reference I would like to tell you that it is better to accept payments on your own website, looks more neat and professional. You can get a payment gateway at authorize.net for a decent price but you also need a merchant account with one of the supported banks. If you are a new project than it is better to use the current paypal paying scheme, but as you grow you should consider upgrading. Other than that the answer to your question is no you do not need an ssl certificate.
There is no point in having an SSL if you are using Paypal, as they have their own and as @jamjar919 mentioned as long as you are not requesting any personal or sensative information prior to sending the user to paypal then its is just an added expense with zero benefit
The only information entered on this php Vsite, by visitors, is when they register for a Vsite account, by entering name, address, city, etc, to get a username & password, which is all stored on the host server database.
You could use an SSL to secure that to give your visitors more confidence in using your site.. But really it depends on the nature of your website. Just think about whether you really need it, but also weight up the additional costs. You'll need the ssl cert and you'll then need a static IP address if your on shared hosting. Definitely work out the additional charges for adding SSL before buying the certificate blindly.