I'm have the same problem.
The last part of the attempted merge:
./clutter-gst-video-texture.c: In function ‘clutter_gst_video_texture_set_idle_material’:
./clutter-gst-video-texture.c:673:7: warning: implicit declaration of function ‘cogl_material_get_color’
make[4]: *** [clutter-gst-video-sink ...