The first file plays until the end and then gapless playback switches back and forth first frame of each video.

Source code to reproduce it:

#############################################################

#!/usr/bin/python
import pygst
pygst.require("0.10")
import gst
import gobject

class Player:
    def __init__(self, filename):
        self.player = gst.element_factory_make("playbin2", "player")
        self.player.set_property("uri", filename)
        self.player.connect("about-to-finish", self.on_about_to_finish)

    def run(self):
        self.player.set_state(gst.STATE_PLAYING)
        loop = gobject.MainLoop()
        loop.run()

    def on_about_to_finish(self, player):
        player.set_property("uri", "file:///tmp/2010/11/26/48/C48_101126T141627115+060-141634693+060_0000040_189.mkv")

if __name__ == "__main__":
    gobject.threads_init()
    player = Player("file:///tmp/2010/11/26/48/C48_101126T141617936+060-141627110+060_0000045_200.mkv")
    player.run()

#############################################################

Files were recorded with gst-plugins-good 0.10.23.

Versions used for playing back:
gstreamer-0.10.31
gst-plugins-base-0.10.31
gst-plugins-good-0.10.26
gst-ffmpeg-0.10.11
gst-python-0.10.20
gst-plugins-ugly-0.10.14
x264-snapshot-20090621-2245