In this listening exercise I understand 'oH wo'chugh...; that means, I hear the l as a w.
This sentence is too ambiguous to be a good example sentence. It might just as easily mean If somebody uses it, they (that person) might explode. In fact, that's the more obvious interpretation of the sentence, given the position of vay' in the first clause.
The problem comes from translating blindly from English. In English, the it has to be stated explicitly, so you know that it's changed from object to subject. There is no such cue in Klingon. And since you can drop pronouns in Klingon, the translator has done so without considering the problems of ambiguity.
So while this sentence is grammatically correct, it is confusing and a not a good sentence for a lesson. If I saw this sentence in anything I was editing, I would advise the author to change it to 'oH lo'chugh vay', chaq jor 'oH. While we're allowed to drop pronouns in Klingon, there is never any requirement to do so, and it should only be done when comprehension will not suffer.