Medibuntu (Multimedia, Entertainment & Distractions In Ubuntu) is a repository of packages that cannot be included into the Ubuntu distribution for legal reasons (copyright, license, patent, etc).
I am generally very wary of suggesting the use of 3rd party repositories. I rarely, if ever, use them myself, even if it’ll make installing an application a bit simpler. The bottom line for this is that I want my machine to be as supported as it can be, so I generally only use the official Ubuntu repositories (main restricted universe multiverse). Adding this repository will add unsupported packages to your system, but it is considered far more trusted than other repositories.