gst-plugin branch_6 cvs fails to build with gcc3.3 as followsdv.c:500: 
warning: unused variable `size'
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o error_resilience.o 
error_resilience.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o wmadec.o wmadec.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o fft.o fft.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o mdct.o mdct.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o mace.o mace.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o huffyuv.o huffyuv.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o a52dec.o a52dec.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o liba52/bit_allocate.o 
liba52/bit_allocate.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o liba52/bitstream.o 
liba52/bitstream.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o liba52/downmix.o liba52/downmix.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o liba52/imdct.o liba52/imdct.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o liba52/parse.o liba52/parse.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/fdct_mmx.o i386/fdct_mmx.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/cputest.o i386/cputest.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/dsputil_mmx.o 
i386/dsputil_mmx.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/mpegvideo_mmx.o 
i386/mpegvideo_mmx.c 
i386/mpegvideo_mmx.c: In function `MPV_common_init_mmx':
i386/mpegvideo_mmx.c:532: warning: unused variable `i'
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/idct_mmx.o i386/idct_mmx.c 
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/motion_est_mmx.o 
i386/motion_est_mmx.c 
i386/motion_est_mmx.c:25: warning: integer constant is too large 
for "long" type
i386/motion_est_mmx.c:26: warning: integer constant is too large 
for "long" type
i386/motion_est_mmx.c:29: warning: `bone' defined but not used
gcc -O3 -Wall -g -DHAVE_AV_CONFIG_H -I.. -D_FILE_OFFSET_BITS=64 -
D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o i386/simple_idct_mmx.o 
i386/simple_idct_mmx.c 
rm -f libavcodec.a
ar rc libavcodec.a common.o utils.o mem.o allcodecs.o mpegvideo.o h263.o 
jrevdct.o jfdctfst.o jfdctint.o mpegaudio.o ac3enc.o mjpeg.o resample.o 
dsputil.o motion_est.o imgconvert.o imgresample.o msmpeg4.o mpeg12.o 
h263dec.o svq1.o rv10.o mpegaudiodec.o pcm.o simple_idct.o ratecontrol.o 
adpcm.o eval.o dv.o error_resilience.o wmadec.o fft.o mdct.o mace.o 
huffyuv.o a52dec.o liba52/bit_allocate.o liba52/bitstream.o 
liba52/downmix.o liba52/imdct.o  liba52/parse.o i386/fdct_mmx.o 
i386/cputest.o i386/dsputil_mmx.o i386/mpegvideo_mmx.o i386/idct_mmx.o 
i386/motion_est_mmx.o i386/simple_idct_mmx.o 
ranlib libavcodec.a
make[6]: Leaving directory `/home/data/cvs/gst-plugins/gst-
libs/ext/ffmpeg/ffmpeg/libavcodec'
make -C libavformat all
make: Entering an unknown directory
make: *** libavformat: No such file or directory.  Stop.
make: Leaving an unknown directory
make[5]: *** [lib] Error 2

It can be made to build by passing CFLAGS="-Wno-strict-aliasing -Wno-error"