Board Thread:Support Requests - Getting Technical/@comment-26332895-20161002184512/@comment-5973717-20161003032456

Custom tags are doable, but if you want a true tag, you'd have to write a MediaWiki extension, and have Wikia install it, which they're not likely to do.

If templates truly don't work for you, and full custom tags aren't an option either, this script on the Dev Wiki uses a duct-tape solution as a substitute for custom tags, for internal use. Perhaps you could use it as a codebase: http://dev.wikia.com/wiki/VideoIntegrator