It should be possible for CryptoParty organizers to reuse/remix existing resources without having to worry too much.
We encourage you to donate your work the public domain (the standard license on this site).
If you require a different license, please clearly embed licensing information into your work. Don't forget to clarify attribution requirements.
If you cannot embed the license into your work, please make sure people will see the license information in the same place where they find your work. (Avoid the media manager, people might find your work without noticing the license requirements.)