I have to trust Guus, creator of this addon, more than Avast. should be easy, because i do not trust Avast, but: 1) no infos about Guus 2) Guus website with no content. Can be anybody even with bad attitude. Perhaps FF Team will check this addon soon, that would be great. this way i will be not safe to use it (sadly)! Update: now i found an project on github (/OhMyGuus/). Guus, why not a few infos about it here ??