Restrict access to webpage from single referrer domain

Hello I need service with redirect or referrer code to Only allow users from specific referrer. Restrict access to webpage from single referrer domain. Here is example as to what is needed. 1. Main site for example ([login to view URL] ) will only have the link url : [login to view URL] [[login to view URL]] Actual video's will be posted on other sites a,b,c,d,e. 2. Only when user clicks link say 2nd link out of 3 links on main site it will take to site a or b and play the video --> redirects to another sites --> [login to view URL] User watches the video on this page and not on main site. 3. If any other user posts directly that url on his pc or even in another tab the Video/Player disappears [login to view URL] . If users join straight on the Site a video will not be visual/playing. 4. Kindly let me know if you would be able to get me such code for redirection/referrer from specific domain. I have the Main Site in Wordpress and the Sites a & b where the links will be posted also in wordpress. I am hoping you have understood what I have tried to explain on what I need. Please message me if need more clarifications. Regards Chris