Laplu wrote:
... and they said it was okay for commercial use.
They are wrong. Legally you need permission to reuse someone else's copyright material, typically given for a negotiated fee. Purchasing a Karaoke version does not come along with a licence for that. Of course if it is for your personal use and gets distributed among a few friends and acquaintances nothing is likely to happen. Should it go viral you could expect copyright strikes, demands for damages, etc. I'm not a lawyer.
You haven't said where in the world you are, and the rules vary by country, but here is one example of relevant advice: https://www.copyrightuser.org/understand/parody-pastiche/:
1. Permission should be sought when possible
A parody will not infringe copyright if the parodist has secured the permission of the rightsholder. Note that the author or artist is not always the rightsholder – it may be a publishing company or a music label. Seeking permission from these entities can be a costly and time-consuming process, and this may discourage small-scale parodists. However, with permission secured, you are free to parody the work within the bounds of the agreed licence, without risk of infringement.
tt2