Concerning adding to your video shown at the Crypt Gallery it might be of interest to add cycling activities of Cycle  Seahaven, a club based in Seaford that organise road rides and off road ones in Friston Forrest. Details of the rides can be found on the club website.
cycleseahaven.org.uk   Andy Lock started the club 3 years ago. I hope this info is helpful.
I agree with you a website embracing all Seaford activities would help.the library have one.Regards,John