Firefox is not responding when i open video sites like youtube

Recently video sites like youtube arent working. as soon as I open a video site firefox goes dark and I haveto close it after which it tells me its "Not Responding" and I haveto Force Quit. Im under the impression its a Flashplugin issue/bug but not sure.
I tried this but with no resolve:

frederick@Dell:~$ sudo apt-get purge flash
[sudo] password for frederick:
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package flash
frederick@Dell:~$ sudo apt-get flashplugin
E: Invalid operation flashplugin
frederick@Dell:~$ sudo apt-get purge flashplugin
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package 'flashplugin' is not installed, so not removed
The following packages were automatically installed and are no longer required:
  linux-headers-3.11.0-12 linux-headers-3.11.0-12-generic
  linux-image-3.11.0-12-generic linux-image-extra-3.11.0-12-generic
  printer-driver-hpijs
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
frederick@Dell:~$ sudo apt-get install adobe-flashplugin
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package adobe-flashplugin is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'adobe-flashplugin' has no installation candidate
frederick@Dell:~$