Pros: Works on more sites than others.
Cons: Japanese subtitles don't include furigana like other dual subtitle extensions.

This is an update of my previous review. The list of cons is down to one. Unless you use Japanese, this is now the best option. This is much improved from earlier releases.

Of course, it is not a"privacy concern" app, because it can see a lot of your activity, but it has great features for the price if you are learning English.