Remove Pop Up blocker

How do I remove the pop up blocker on Firefox for certain websites? I am doing an online course and each introduction for each chapter has a short video that pops up but as soon as that happens Firefox sends a "Critical error" message then the video stops so I thinks that's happening because pop up blocker is turned on and I just dont know how to turn pop up blocker off for specific websites only like this one I am using for my study course. How can I turn the pop up blocker just for this one website so that this doesn't keep happening?