You don't need to do anything to secure the copyright in your artwork. That came about automatically when you created it. It would be as well to gather as much evidence as you can which shows that you are the author of the work, but since I assume that neither the band nor the director of the video are likely to claim that they created the artwork, the question of authorship is unlikely to be an important element of your claim.
One factor which may cause a problem is where the mural is/was situated. For instance if it is street art and you didn't have the permission of the building or land owner, the defendant might try to counter your claim by saying this was criminal damage and therefore you shouldn't be able to profit from it. A few years ago such a defence would probably have succeeded but following a some successful cases in the USA, I think a UK or Dutch court might less inclined to accept that line of argument today. Either way there is no dispute that if you created the artwork, then you own the copyright in it. This is something which the activities of Banksy
have helped to establish in recent times (more on this here
However assuming that your mural was done with the permission of the owner of the structure on which it is painted, then the other likely argument that could be run against your claim is that as it is/was a work of art situated in the public realm, the director of the video would be covered by the provisions of section 62
of the UK's Copyright Designs and Patents Act 1988. However this would not be a valid defence because your mural is neither a sculpture nor a work of artistic craftsmanship, just a work of art which means that section 62 would not apply.
Since you are considering using the Dutch courts, it is worth noting that the Netherlands has a fairly similar legal position with regard to certain works of art located in public places. Sadly I don't speak Dutch so I have had to rely on Google translate, but it appears that signs and decorative metalwork, along with buildings, sculpture and topographical models are the only things which, when located in a public place, may be freely photographed or filmed without it amounting to an infringement of copyright.
The exact text (in Dutch) refers to: "teeken, schilder, bouw en beeldhouwwerken, lithografieën, graveer en andere plaatwerken; ontwerpen, schetsen en plastische werken, betrekkelijk tot de bouwkunde, de aardrijkskunde, de plaatsbeschrijving of andere wetenschappen". Google Translate says this means: "sign, painter, construction and sculptures, lithographs, engraving and other sheet metal work; designs, sketches and plastic works relative to architecture, geography, topography or other sciences". The one word which appears to be ambiguous in translation is 'schilder' which Google says means 'painter' but that doesn't make any sense in this context*
. From my knowledge of German (which is closely related to Dutch) Schilder
is the plural of the word for signboard or nameplate, which I think would fit this context better. However before going ahead with bringing a claim in the Dutch courts I suggest you should get confirmation from someone with knowledge of Dutch caselaw that the Dutch courts would categorically exclude your mural from the list of exceptions. The relevant part is Article 18 of the 1912 Dutch Copyright [Auteurswet] Act
As this claim is relatively straightforward, you could start a claim in the UK using the small claims track
of the Intellectual Property Enterprise Court (IPEC) without needing a lawyer. However as far as I am aware there is no comparable 'do-it-yourself' system in the Netherlands and in any case unless you speak Dutch, it would be too complicated to start a claim there without using a lawyer to help. You can certainly use the Dutch courts as the video is available there, even if you and/or the director of the video are British citizens.
I hope this helps set you on the right path.
* Afternote. Checking the link to the Dutch Auteurswet Act again I notice that the actual text of Artcile 10 to which Article 18 refers, is schilder-[...]werken
, which Google translates as 'paintwork'. I doubt that this means that a mural might be included in the exception, but it makes my advice that you check out the legal situation with respect to Dutch law even more imperative, before starting a claim in the Dutch courts.