This file gives a compile error:

------------------------------------------------
\documentclass{article}
\usepackage{amsmath}
\usepackage{easybmat}
\begin{document}

\begin{multline*}
\bgroup
\renewenvironment{pmatrix}{\left(\begin{BMAT}(@){c.c}{c.c}}
{\end{BMAT}\right)}
\begin{pmatrix}
A & B\\
C & D
\end{pmatrix}
\egroup
\end{multline*}
\end{document}
----------------------------------------

htlatex foo.tex "htm,mathml"

(/usr/local/texlive/2014/texmf-dist/tex/generic/tex4ht/html-mml.4ht)
(/usr/local/texlive/2014/texmf-dist/tex/generic/tex4ht/html4-uni.4ht))
(./foo.aux)
l.15 --- TeX4ht warning --- \halign translated into linear text ---
! Missing # inserted in alignment preamble.
<to be read again>
&
l.15 \end{multline*}

?

Reference:
http://tex.stackexchange.com/questions/163746/tex4ht-compile-error-using-mathml-switch-using-multline-with-pmatrix-and-easybma