[kurkosdr]

Originally Posted by Ghitulescu

Since DivX Networks (now DivX inc) licences the divx use, format and logo for standalones, it's no wonder their encodes work the best on them.

Nah, I don't think the reason non-Divx Inc tools produce excessive bitrate spikes is because of lack of documentation (the bitrates and settings to make a Divx-compatible avi file are well known). More like lack of interest by Xvid. Most non-Divx Inc tools use Xvid, which can't stay within the required bitrates in one pass mode (only in two pass mode), and most tools just use the one pass mode (faster) and just don't care about the bitrate spikes. I now switched to Avidemux, with Xvid as the codec, with "Average bitrate (two pass)" set accordingly (see video above).
I use Divx Plus Converter only for fast encodings when I don't care about the quality of a particular video file.