gst-launch-0.10 -q \
  videotestsrc num-buffers=20 pattern=ball ! \
  video/x-raw-yuv,framerate=24000/1001,interlaced=false ! \
  interlace pattern=2:3 allow-rff=true ! \
  deinterlace ! \
  ffmpegcolorspace ! \
  pngenc snapshot=false ! \
  multifilesink location=%05d.png

Look at output png files.  00000.png and 00001.png should be nearly identical.  Output png's should be identical in sets of 2's and 3's, 00000 & 00001, 00002 & 3 & 4, etc.

method=linear gets it right.

Also, there should be 50 png files created, however, there are only 47.