I knewow of an extension for Chrome, "Subtitles for Language Learning"."

US alternatives

I know of an extension for Chrome called "Subtitles for Language Learning."
I'm using an extension for Chrome called "Subtitles for Language Learning."

At least in Japan, Prime Video offers audio in foreign languages voice and Japanese subtitles or Japanese dubbing.

Using this extension, I can watch movies and dramas with English voiceaudio and subtitles.

We don't usually use the word, "voice," like this as we do in Japanese. It's more like a set phrase where we choose the audio and subtitles of a show.

In addition, I can immediately search for the meaning of unknown wordswords I don't know by putting the cursor onver the subtitle.

"cursor over the subtitle" is a set phrase.

I knewfound an extension for Chrome, "Subtitles for Language Learning".

この文章には「knew」は過去形みたいです。絶対に「knew/know」を使いたいなら、「I know of an~」が使えますが、例を挙げる言葉です。そこで、「I know of an extension for Chrome, "Subtitles for Language Learning"」が言えませんが、「I know of an extension which can/lets you add subtitles to videos you watch on Amazon Prime. It's called "Subtitles for Language Learning".」は自然です。

At least in Japan, Prime Video offers either foreign languages voice audio and Japanese subtitles, or Japanese dubbing.

「either」+「,」に入れったら、もっとわかりやすくなります。

Using this extension, I can watch movies and dramas with English voices and subtitles.