You'll may want to check you sound out put. I know it sounds really stupid, but
atlas the alsa has changed. You will go forth to the ALSA mixer in terminal
mode. This if I recall right. Because I has the same problem and was easy fix.
So open up thy terminal in Appilcations >Termial and type in alsamixer. Turn up
master and the rest of the goodies options. Then reboot and the sound should be
piping through. If the red X is over the speaker double click and proceed to
adjust the out put.
 As for vids playing on Youtube. Double check to see if the restricted CODECS
are in stalled through Synaptic.
 If you seem NOT to get the ever looping at the log in splash screen. Once
again this only effects the CRT monitors and not the nice flat panels. You must
go into display and choose a higher quality. So if you have lets say set at
1024x768. You got to one up it. To lets say 1280x1024 .Despite my protest. It
is better than the every looping of hell.
 You can have better functions of the net by using Epiphany web browser stead
of Fire fox. The flash works and the games on FB are not F uped.