I used ubuntu 14.04 and noticed that Adobe flash player does not come preinstalled. This is need for websites like youtube. To manually install flash player, there are 2 steps. First install adobe flash player and secondly install the flash player plugin. Its easy!
Installing Adobe Flash player and plugin
1. First download the tar.gz file from adobe.com website for linux.
2. Unpack it you find a file libflashplayer.so
3. Copy it and paste it to this location /usr/lib/mozilla/plugins
sudo cp libflashplayer.so /usr/lib/mozilla/plugins
or if you prefer GUI
sudo nautilus
This will open up files window with proper root permissions to copy.
4. Finally, to install the flash plugin for firefox, just click on ubuntu software center, type “adobe flash”, install it.
5. Restart your firefox and you are all good to go with flash player
