Your solution is nice and Perlish, but (if you care), I would have implemented it like this:

find /the/start/dir -type f -exec perl -i~ \
    -e 's/origtext/changedtext/g;print' {} \;
[download]

If you wanted to limit it to html files only, then a

find /the/start/dir -type f -name '*.html' ...
[download]

would have worked. In fact, using sed or tr instead of Perl would work, 'cept I don't know how to do inplace editing with them.

Of course, this doesn't have the reusability factor of your solution; but in this case I would have sacrificed it for quickness.

A big part of administration is knowing the right tool for the job.