I completely avoid using any music that may have a copyright issue. There are plenty of sites online where you can find Public Domain or Royalty Free music. The main site I use is Incompetech. You can use any of his music for free, and he has other sites listed where you can find free music for your reviews. It's my understanding that it's preferred we use that kind of music, but I've seen loads of videos with popular music on them, so you obviously won't get in trouble for doing it - it's just a personal choice I make.

The only song I've ever used was decades past its copyright date, and I got the .mp3 file by stripping it from a youtube video of a guy's player piano playing the song. I did credit the name of the song and the youtube user that owned the piano, all the same. If I knew how to credit the person who keyed the player piano reel, I'd do that too---but I'm pretty sure whoever-it-was is no longer alive.

I don't think I'll ever use music that's still in current copyright, because I'd be sad if one of my videos was ever taken down.

It's illegal to use copyrighted music in your videos without licensing - on Youtube or anywhere - unless you can argue "fair use" or the terms of the copyright makes a specific allowance of this specific usage. This is common sense. The terms of copyrights are all very different, and each song and/or record will likely have idiosyncratic differences in wording. Most popular music, however, is subject to the same sorts of ironclad copyrights that do not allow for the kind of use you are describing.

Edenfantasys and Edentube do not have any licensing agreements with any entity that holds copyrights to music. Edenfantasys also makes it clear in their Terms & Conditions that if you do something illegal on their site, you are bound (by agreeing to the Terms & Conditions and electronically signing that contract) to accept full responsibility for any legal action brought against the Edenfantasys corporation because of your illegal actions. People do it all the time, but it's not wise. Should any of those copyright holders come across these infringements on Edentube, you'll be lucky if all they do is request you pull it from the site.

For some reason people think that crediting the song's singer or copyright holder will cover their asses. This is not true. The only thing this does is tell your viewers who sings the song or holds the copyright. It does not buy you licensing of the song. Things that have rights reserved under protective contracts like Creative Commons can be used in this way, but again, most popular music does not use this kind of protection.