12.04 update breaks video

[rikona]

On Fri, 1 May 2015 12:03:50 +0100
Colin Law <clanlaw at gmail.com> wrote:

> On 1 May 2015 at 06:29, rikona <rikona at sonic.net> wrote:
> > Just updated 12.04 and video is broken. Neither VLC, Movie Player,
> > or Dragon player will show the video part of MP4, avi, or wmv files.
> > Dozens of MP4s that used to play just fine are all broken. Trying to
> > play these in Ffox gives "file is corrupted". A 14.04 box, recently
> > updated, plays MP4s just fine. The audio part seems to be fine -
> > just a black screen instead of video. . How can I find out what
> > happened and fix it?
> 
> Do you see anything helpful if you run
> vlc somefile.mp4
> in a terminal?  Where somefile.mp4 is one of the files obviously.

Thanks for the reply.

No - it opens the player window, gives audio, has black screen - no
msgs at all.