I just got it, and it was going well for a while but shortly after, scanning any word gives a "word not found" popup that says to instead try ai lookup in the paid plan, although for now clicking words in subtitles works for me still. It's nice that when you click a word in the subs it pauses the video (I've tried only in YouTube), the gifs can be very unrelated but i find it funny.

sometimes the subtitles group letters wrong so it misunderstands what words are there, I'll give an example: in the Japanese sentence 眠くなるとかはあんまりなくて, it groups/highlights the area はあんまり wrong, highlighting はあ, ん, まり separately when they are separated as は あんまり -> wa(is) anmari(barely), making you unable to click anmari to look up. The autosubs are not perfect sometimes, missing some things when there's really quick/casual speaking, example: registered 勉強捗ってる？ (benkyou hakadotteru?) as 勉強はってる。(benyou hatteru.), missing the word 捗ってる(making progress) in "are you making progress on your studies?". or mistaking kanji like 称賛 (shousan) as 小さ ("shousa")