It's really easy!
Click on the video.
You will be transferred to a product page where you can add the film to the cart.
Follow the process to pay on Mon Cash (in Gourdes) or on Paypal or credit card for other currencies. You will also need to log in or create an account if you don't have one.
After paying, the payment platform will take you back to the site. Return to the film page to watch it.
Always check that you are logged in every time you want to watch the movie again.