A friend of mine give me better rules for jesred. You can now browse the repository in the browser:

regex ^http://((.*)archive.ubuntu.com/ubuntu/(dists|pool)/.*(deb|bz2|Release|Release.gpg))$ http://apt-cacher:3142/\1
regex ^http://(security.ubuntu.com/ubuntu/(dists|pool)/.*(deb|bz2|Release|Release.gpg))$ http://apt-cacher:3142/\1

Thanks Jerôme!