Yes it will. You need to gain permission from the user OR pay for a license through the label that the artist is under. If it is free to use music like MicroAudio stuff then you are fine.

The determining factor will be if you become partnered or not. If you become partnered you will need to take it down or do the steps above. If not then yeah you can use the music but Youtube will make it so that they make money off your video instead of you.

Great! I can use music in my videos if I can ever reach to make videos

Then you're going to want to have him write out a formal letter stating he gives you permission.

^This and so you can dispute when Youtube is fucking you over. WHICH HAPPENS 95% all the time!

I would stick to copyright free, royalty free music if you are going to be using it as background music through out the video.

I occasionally throw a mini sound byte in from a popular song, but nothing more than 5 to 10 seconds, I also usually edit the audio properties of it ever so slightly so the wavelengths aren't as recognizable though youtube audio scans.

Ultimately, using anything that isn't copyrighted without formal permission is illegal. This includes music for videos, stock images for thumbnails, etc. You put yourself at risk any time you use anyone elses work.

Realistically though, the chances of someone going out of their way to pursue you on youtube is quite small if you aren't a total idiot about it.