Due to legal reasons, some packages are restricted by copyright in some countries, so Ubuntu does not come with some codecs like audio, video, Flash and Java installed. However it permits you make the installation of them but this will be your decision.
If you decide by the installation. Open a shell and type:
sudo apt-get install ubuntu-restricted-extras
Regarding Flash codec, see the post How to fix Adobe Flash Player in Google Chrome in Ubuntu 64 bits whether you have Ubuntu 64 bits.
That’s it folks. See you next time.