Mine

$ echo xx__SRCxxx | sed "s/__SRC/   `  echo ./yuv/foreman-qcif.yuv | sed 's/\./\\\./g;s/\//\\\//g' `   /g"
sed: -e expression #1, char 20: unknown option to `s'
xx      xxx
$ 



==========

== escapes correct BUT sed refuse to accept it inside s// :/ ==

$ echo ./yuv/foreman-qcif.yuv | sed 's/\./\\\./g;s/\//\\\//g'
\.\/yuv\/foreman-qcif\.yuv