What do you do in this situation?

You've clearly mentioned in your terms of service / contract that their highlight video will be used for promotional purposes.

They're happy with the video, but want you to take it down and then say "oh sorry, I didnt realise you would be uploading it to the internet" ...

Absolutely winds me up when I get this. I do the whole " how else am I meant to get business if everyone asks me to remove their video " plea and the fact only brides interested in booking me can see it via my website ... And also clarify how photogenic and great they look etc. But in the end if they really get ultra fussy for the sake of not making them upset (as I want repeat business/referrals) I just remove it.

I've quoted certain people very low because when i've met them I realised how great they would look on my portfolio but then they turn around and ask to have it removed ...

I honor their request. Some people have very legitimate reasons for not wanting to be posted online. Even if it's simply a preference, it's a small price to pay to keep them happy. Our client for April 26th did the same request, and I'll still put it online, with a password for her, so she can see it or share it if she wants, but I"ll keep them private. I presume I will also skip the blog post about them.

Oh, well. As long as its not a majority, let it go. If it really is a lot of people, and is that valuable to you, maybe start asking about it before quoting a price, and offering two different prices based on whether you can use the materials or not.

Had this occurring once, after one year that the trailer was on my site the client send me a mail saying to take it off as she thought one year was sufficient for me to use her film as advertisement.

I don't put this in a contract that I have the right to use a trailer of every wedding I capture on my website, I know it is important to have demo's but forcing clients to show their wedding for the whole world to see would lead into many lost jobs, where I live they value their privacy and only thing I can do is to ask real nice and hope they won't reconsider. What I have done a few times, mainly with trailers from which I know will provide me new work is to give the trailer for free but to ask to have it on my website for max 2 years and put that in writing and have it signed. In that case I give your client a choice and pay them for that use since I will be making more money from their footage.

As previously discussed on another thread ... I don't emphasize on the fact their video will go on my website as to not scare them away with too many terms & conditions. That's the last thing anybody wants to hear when booking a service.

It's just written in the service agreement that I send when I receive a retainer. Along with things like 'acts of God / emergencies'.

It's becoming a majority now though that want their trailers removed hence why I thought i'd create this thread ...

I think offering two price plans sounds good. Will have to give that a try.

If you just offer the trailer for free IF they allow you to place it online for X period then at least you have the certainty how long you can use it, I would say 2 years would be sufficient so you would have plenty time to add new trailers every 1 to 2 years.

Some people think that privacy exists today lol
If you don't take them off they might make a stink and you don't need that