- nonexclusive, because they're not demanding exclusive rights to your content. If they did, there's no way this would fly.

- royalty free, because otherwise you could charge them money for doing anything with your data, even things you've asked them to do.

- worldwide, because you may ask them to communicate with servers in other countries. i.e. you are using Firefox Sync to sync your bookmarks and you travel overseas, your bookmarks are now traveling between two countries.

The question is "why do they need a license at all", IMO. The qualifiers on the license all make sense to me. It's possible additional qualifiers like 'short-term' could make it less scary.