Here it is how I proceeded to install Texlive 2013 and now media9 is working!
First I removed everything which had been previously installed in Ubuntu 12.04 as suggested by @texenthusiast which can be found on this link: How to remove everything related to TeX Live for fresh install on Ubuntu?.
Secondly I downloaded the install script as suggested by @scottkosty which can be found here Install script for TeX Live on Ubuntu. It actually uses the Texlive 2013 installer and there were 2775 files which had to be downloaded for the complete installation. But because of my internet connection which was disconnecting after every 20-30 minutes, the installation was restarting but it used to read the files which were installed earlier so it did not download those files but the new one. But later on the installation was stucked on file 1705 and it was not proceeding and the installation was restarting. It happened number of times with me, so I decided to download the actual texlive 2013 installer from here Installing TeX Live over the Internet to give it a try. I am sure that install script suggested by @scottskty can work for others and for me too but I did not want to remove all the files and install again from the start.
I then proceeded with the texlive 2013 installer as suggested here TeX Live - Quick install. It did the same thing again read the files which were installed earlier and at reaching 1705 file it said Partial download of so and so file found removing it. So it removed the file and downloaded it again and then the installation continued and downloaded all 2775 files.
After the installation finished, I added the directory of TeX Live binaries to PATH. I did it in
/etc/profile. I opened a terminal and wrote:
sudo gedit /etc/profile
which opened the profile file in gedit text editor and then I added the line at the bottom and put a comment too:
# This path is for TEXlive2013
Finally I did the things as suggested here TeX Live and Debian/Ubuntu found in the section Integrating vanilla TeX Live with Debian. This is also found in the answer suggested by @Canageek.
I really thank you all for your help in this regard.