Legal questions about crediting a system used in a game

Update:
So we contacted him and after a few messages through YouTube this is what he says:

To:BlackHorizonnStudios
You didn’t answer my question – I’m giving you two options – is marking it private adequate or you want it deleted (I’m not modifying the description to say anything different) ?

If I tell him to delete the videos I feel like he’s going to try to bad mouth black horizon studios. We also asked him if he could offer his invoice number, we asked him 3 times and each time he avoided the question. So he obviously didn’t buy the system legitimately.

So what should we do?

Original:

If someone is using your system do they have to give credit?

I saw a video of someone using our system UniStorm, a dynamic weather system, in their game and they said they made it.

Don’t they have to credit us and our system?

He never once says UniStorm and in the description he says we created a dynamic day and night weather system. We only have this on the asset store I know their terms of use says that they have to give credit to products or tools used?

Video to showing it

As Fattie said, it really depends on the term of sale. You could post a comment on their youtube video, and say how thrilled you are that they are using your tech. You could contact them (presumably you can figure out who they are) and ask if you can link to their youtube video from your website, so others can see what your tech can do. Worst case they have got your tech without paying… but if you like their demo, see it as free promotion.

http://unity3d.com/unity/faq

In most cases, you can use assets for commercial products . FAQ

It will be very difficult to prove anything much less prosecute. You will need to contact YouTube piracy @Submit a copyright removal request - YouTube Help

If you choose to get a lawyer, proceed do this first and have your attorney(s) to forward documents requesting YouTube a take down notice of infringement. If you think this user is reselling your system without your permission you can request from their ISP and host providers a DMCA take down policy and proceed with you legal obligations. You are protected under the DMCA, but you just have to prove it is your system (eg: technology, programming code)under the laws and jurisdictions of your Country and State.

Please note: I am not a lawyer, nor is this legal advice just my unbiased opinion.

So we were finally able to verify the invoice number, he was a customer, but he just wanted to take credit for our system. He refused to change the description and threatened us and guess what happened?

So he violated his terms of use and he returned the system, was refunded the full amount, said he will leave a bad rating, said he would leave a bad review, and post on our forums bad mouthing our system. He needs the system so we know he will continue using it.

This is bull s**t.

I contacted the asset store team letting them know our situation and I really hope they understand give us back the refunded amount. If not, I’m very disappointed in the way the asset store handled this and it’s an outrage.