Ok, This happens all the time and once in a great while, I will rant about this on my community’s voice server. I hate it when people reupload content without consent or even credit the work. This happens far too often… The author to a Undertale Remix “Waters of megalovania” by BotanicSage I enjoy greatly and listen to it far too often… but any song I enjoy I will listen to over and over. He has been getting people taking his work and on at song’s page he made a message there:

BotanicSage [BS]2 weeks ago (edited) (Source)
People have been uploading this track everywhere without any real credit to me. Many of you have contacted me informing me of this and unfortunately, there’s not much I can do about it. In an effort to let others know about the initial video the mix came from, I unfortunately had to add something to the title of this video. Sorry. Also, to the people out there who upload other people’s works without crediting them, it’s a shitty way to show appreciation towards something someone made that you liked, but that’s just in my opinion, I guess.
Honestly, it is a “shitty way” to show any support to an artist… It’s the same for artwork that doesn’t have any sources. Anyone doing this is ‘stealing’ artwork and its something google got in trouble for in the past for. If you can’t find the Original poster… then you should state clearly “I found this but I dunno who made it… where is it from?” at least maybe your group or followers and give you a heads up and you can credit the right one. Laziness isn’t an excuse for stealing work…
If it’s clearly stated the artist doesn’t care or don’t want to be credited then ok… otherwise something that shouldn’t be done so often and should be corrected as soon as possible.