Should I install the ubuntu-restricted-extras package?

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http://askubuntu.com – I installed Mozilla Firefox beta 9 and the Mozilla flash plugin as a .tar.gz file. I unpacked it, installed it and now I can watch Youtube videos smoothly. But I want to play mp3 codecs and other restricted stuff on my laptop. Should I uninstall the flash plugin for Mozilla Firefox or just install the ubuntu-restricted-extras package (which contains everything I need)? If I install the package without uninstalling the Mozilla plugin, will anything bad happen? (HowTos)