Trouble playing MP4 videos under Fedora 21 -- Gstreamer thinks a codec is missing which is actually installed

[Andras Simon]

2015-01-07 18:19 GMT+01:00, Jonathan Ryshpan <jonrysh at pacbell.net>:
> MP4 videos played OK under Fedora 20, but when I attempt to play one
> under Fedora 21, I get a popup from Dragon Player (KDE's default video
> player).
>
>         Dragon Player requires additional plugins for this operation
>         MPEG-4 AAC decoder
>         MPEG-4 Video decoder
>
>         The following plugins are required.  Do you want to search for
>         these now?
>
> When I click Continue, after a delay to download a cache, I get this
> popup:
>
>         To be Installed
>
>                 gstreamer1-libav
>                 gstreamer1-plugins-bad-free
>                 gstreamer1-bad-freeworl
>                 gstreamer1-plugins-good
>
> But when I click Continue, after another delay to download a cache, I
> get this popup:
>
>         The package that is trying to be installed is already installed.
>
>                                         Details
>
>         gstreamer1-plugins-bad-free-1.4.4-1.fc21.x86_64 is already
>         installed
>
> System is
>
>         4 processor x86_64 (AMD)
>         Nvidia Geforce 9500GT video card
>         Fedora 21 with all updates
>         Nouveau video driver
>         KDE 4.14.3
>         Dragon player 2.0
>
> Where do I go from here?

To mplayer?

Andras