Its hardly a surprise the latest isnt working given their still offering the much earlier version
1.6.5.5. on their site
https://addons.mozilla.org/en-US/fir...ehost-grabber/
I do wonder how great the differences are between the above
and the developers latest version
I use the earlier version occasionally with the latest ff and havent had any issues
Playing devils advocate - using an earlier version of any browser could be a risky thing
looking at how many vulnerabilities are fixed from one version to the next
https://www.mozilla.org/en-US/security/advisories/
dates of versions
https://en.wikipedia.org/wiki/Firefox_version_history