With GStreamer you actually don't need sockets to do IPC: the whole stream framework runs in a separate thread that you can access using method calls/messages.

If you use the standard playbin plugin as a base, you can probably set up a complete audio/video player in something like 10 lines of code (a couple more if you want to hook in custom audio/video processing).

Gst works fine with Tk at least for audio playing (I haven't tried video), as long as you make sure you're syncing the Tk and Glib event loops. I devised a fairly hackish way of doing that, by polling the Tk events from within the Glib mainloop:

# setup glib loop
our $loop = Glib::MainLoop->new(undef,0);

# handle tk events
sub tk_loop {
  my $c = Tk::MainWindow->Count;
  if ($c) {
    1 while (DoOneEvent(ALL_EVENTS | DONT_WAIT));
  }
  else {
    $loop->quit;  # quit glib loop if GUI is closed
  }
  $c;
}

Glib::Timeout->add(5,\&tk_loop);  # call tk_loop every 5 ms

$loop->run;
[download]

This appears to be more than sufficient to run Tk and Gstreamer with good responsiveness, and you can probably reduce the interval for tk_loop if that takes up too much CPU resources.