Would it also be okay if I remixed them too? Credit will be given for the original.
Sure! As long as you don't resell/redistribute the remixed songs by themselves, feel free!
But what if I make a youtube video featuring the remixed tracks? Does that count as redistribution?
No issues with putting them in a video! Redistribution would be if you posted the audio assets themselves for people to download, like placing the project files on GitHub or reselling them
