Looks like from the video that it can be repaired.
You know your van is only 8 years old and considering our van is 31 years yours is yet a pup. Having read so many of these issues on new vans I honestly think the caravan manufacturers should be made to take a long hard look at themselves. Personally, I doubt a lot of them are designed to be fit for purpose, I don't think it's too much to ask for a van to be leak-free for 10 years in this day and age.
If I was you irrespective of who you bought the van from you I would be making a strong complaint to the manufacturers, these people need their arses held to the fire. When you consider the new version of your van is £28k personally I'd expect better, if I can buy a car with a 10-year warranty and a car gets much more exposure to the road etc and it remains leak free then surely caravans should be the same, shudder to think if caravan companies made cars how poor they would be.
Anyway, good luck with getting it fixed but send a hot email to the manufacturer you never know what they may say.