If you haven't installed the ubuntu-restricted-extras package, try that.
Of the three sites you've listed, the first was unable to deliver any page when I loaded it; it appears to be down now. The second site worked fine on my Ubuntu system. The third had so many pop-ups, I was discouraged from persisting to figure out how one is supposed to play music on it.
But my success with the second site suggests you should be able to get them working, without too much trouble.
ubuntu-restricted-extras will give you most of what may be needed.
Another thing that may help is to enable the Medibuntu repository (as mentioned in one of the answers to the above linked question) and install codecs and related packages from that.
To do that, run these commands:
sudo -E wget --output-document=/etc/apt/sources.list.d/medibuntu.list http://www.medibuntu.org/sources.list.d/$(lsb_release -cs).list && sudo apt-get --quiet update && sudo apt-get --yes --quiet --allow-unauthenticated install medibuntu-keyring && sudo apt-get --quiet update
sudo apt-get install app-install-data-medibuntu apport-hooks-medibuntu
sudo apt-get install aacgain aacplusenc alsa-firmware libavcodec-extra-53 libavdevice-extra-53 libavfilter-extra-2 libavformat-extra-53 libavutil-extra-51 libdvdcss2 libdvdcss-dev libpostproc-extra-52 libswscale-extra-2 mplayer-dbg mplayer-doc mplayer-gui mplayer non-free-codecs rmconverter w32codecs
If you're running the 64-bit version of Ubuntu, replace
w32codecs (at the end of the third command) with
w64codecs. The third command may warn you:
The following packages will be REMOVED:
libavformat53 libpostproc52 libswscale2 mplayer2
The third command above installs what I consider to be the most useful packages provided in the Medibuntu repository (minus the
ices package which is currently not installable on many machines because it depends on packages that are not available). Please note that it is possible that there are legal restrictions applicable to you that could render your installing or using of some or all software provided in the Medibuntu repository unlawful. Please make sure to read this page to understand the nature of the software Medibuntu provides, and take note of its disclaimer, which applies to this answer also:
It is your legal responsibility to make sure that the software you are installing can be legally used in your country and for your intended purpose.