I'm new to Ubuntu and I'm having difficulty watching videos. How can I install the video codecs needed for most video formats?
Normally when you install Ubuntu in the installer it asks you to install 3rd party stuff which includes this codecs for video/audio.
Click here: ubuntu-restricted-extras
It will ask for some additional dependencies, just say yes. Then click on the apply button. This will install not only the codecs you need but many other things including fonts, flash support and more.
Besides, though on Windows platform software called VLC ( VideoLAN Player ) is "codec-less", in Ubuntu world it also removes you from many small glitches inside gnome offered pre-installed players like Rhythmbox and Totem. I might be mistaking, but some of them rely on GStreamer problems.
Consider downloading and using it also, especially if you prefer DVDs and torrents...
I think upstream version was in ubuntu-univerese repozitory, that should be enabled by default in freshly installed Ubuntu OS, so you only have to open Terminal and write this:
Hope it helps for not only you, but other readers.