Is very simple
If you use firefox a simple addons https://addons.mozilla.org/es-ES/firefox/addon/video-downloadhelper/
or
Umplayer:
UMPlayer is the media player that fills all your needs. With dozens of advanced features and built-in codecs it can handle any media format, and can play Audio CDs, DVDs, (S)VCDs, TV / Radio cards, YouTube™ player/save and SHOUTcast™ streams and even incomplete or damaged media files.
Installation
it works with FC14, FC15, fC16, FC17, FC18
32bits
su -c 'yum -y localinstall http://sourceforge.net/projects/umplayer/files/UMPlayer-0.95/Fedora_14/umplayer-0.95-2.1.i386.rpm'
64bits
su -c 'yum -y localinstall http://sourceforge.net/projects/umplayer/files/UMPlayer-0.95/Fedora_14/umplayer-0.95-2.1.x86_64.rpm'
sudo dnf install youtube-dl
. All you need.