Just like every other language. When one speaks their native language, words tend to run together. And naturally, there are two "o"s next to each other, so it seems like there is only one "o". I can hear two. Try using headphones with the audio questions. It helped me a lot in the beginning.
If I imagine that הילדה לא סה את זה were a Hebrew sentence, I'm not 100% sure it would be pronounced differently (if the recording here could be interpreted this way, and if I'm making I difference if I say both sentences). If there is a pronunciation difference, I think it's microscopic.
The two phrases are somewhat nuanced in their individual meaning, so there is a difference between what she "is doing" (continuous aspect; a currently ongoing [also known as incomplete or imperfect] action) and what she "does" (punctiliar aspect; used to denote an action happening in a single point of time), but Hebrew and english express this differently. English expresses these aspects as explicitly separate: "is doing" and "does." Hebrew, however, expresses it contextually in a singular present tense: she "is doing/does." If English expressed it singularly, it would look something like "What is she doing/does?" " Oh, she is running/runs in a race. " In context, the most comfortable meaning expresses itself immediately. Out of context it makes no sense, but as you better understand a language and speak it more fully, its idiosyncrasies slowly become normal and commonplace.
Unfortunately, if you need things to perfectly, literally translate the same way across the board... I'll have to refer you to the math department. All language is abstract by nature. It follows rules, but those rules aren't grounded in unchangeable fundamentals like in mathematics. You know you have three apples because... well... there's three of them, and they're apples. What more do you want from me!? But language... Ah, blessed language... It is not "burdened" by fundamental unchanging concepts, so rules have changed based on rules that have changed based on rules that have changed. The most "fundamental" (as it were) thing about language you can ever really learn is that ALL language is ultimately idiomatic. All language requires it's context. If you want the literal definition of things you will often never find the actual meaning of things, because language is only part structure. It's also part self expression, and is therefore subject to the influence of the ever-changing nature of self.
All that to say "there is no structural distinct between the two, but don't worry. Let the language change the way you think, instead of letting how you think change the language, and it'll come together all in good time, I promise!"