is it okay to put remix of songs on youtube?

[Den B7]

If you have written permission from the copyright holders from the songs that you use, then it's okay to make a remix.

Without permission, you are still violating copyrights and that is illegal and against YouTube policy.

To understand the worst that could happen for those who violate copyright laws, read below:
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http://new.music.yahoo.com/blogs/amplifi...-24-songs/

Minnesota Mom Hit With $1.5 Million Fine for Downloading 24 Songs
Posted Thu Nov 4, 2010 10:38am PDT by Daniel Kreps in Amplifier
What's the value of a song? Jammie Thomas-Rasset has spent the last few years in court debating that question. The Minnesota mother of four is being penalized for illegally downloading and sharing 24 songs on the peer-to-peer file-sharing network Kazaa in 2006, but how much she owes the record labels has been in question. The jury in her third trial has just ruled that Thomas-Rasset should pay Capitol Records $1.5 million, CNET reports, which breaks down to $62,500 per song. It's a heavy penalty considering the 24 tunes would only cost approximately $24 on iTunes