From the source code, "ffmpeg2theora" by default puts the value of keyframe interval at 64 (for one-pass mode) and 256 (for two-pass mode).
No video is transcoded well.
After experimenting with some values (while having a lot of pain with blocky OGV outputs), according to my experience the default value should simply be 16, for either pass.
It doesn't matter whether you have VERY HIGH video-bitrates. If you have these default values for keyframe interval, your videos will have pixelation.
Sigh!
