Tell me the exact process that you did to make the music file, starting from downloading the original to exporting it in audacity.
Sure.
I went onto Firefox WITH the addon DownloadHelper, a video download program. Went to YouTube, searched the video, and downloaded it, but it downloads as an .flv file, and audacity won't open that file.
There ya go. What happens? The song plays incorrectly when I play it. That's the problem. I can't make it good.

Oh, it's when I change the extension upon save as.