Translation:Good morning, do you want an egg with your breakfast?
Yes, I thought it was 'aardbei' on the fast version, but on the slow version I could hear the difference. It's good that Duo has both! I think audio is difficult in any language because people often speak quickly, and when you're not a native it can be hard to pick up those reduced pauses.
No, "bij" and "met" can both mean "with," but in different ways. But first, if you wanted to offer an egg near someone's breakfast you'd use "nabij." Why you'd want to do that is an exercise I leave up to someone else. :)
"Met" means "with" as in "together". "Ik loop met hem" (I walk with him) ,"Ik zwem met mijn hond" (I swim with my dog, I am swimming with my dog), etc.
"Bij" means "with" too, but in the sense of "along with" or yes, "next to." Dutch really likes to work position and orientation into its grammar... Imagine that your sandwich is already on the plate and someone's offering an egg. "Do you want an egg to share the plate with your breakfast?" That's more the translation of "bij" in this case.
I am sorry to moan about this again, but "Goedemorgen, wilt u een ei bij uw ontbijt?" is not what I can hear the woman saying in the example. For exercises like this, her ennuciation is far from ideal. Try as I might, even using the tortoise, "wilt" is not the third word that she utters!
This sentence roughly sounds like (WiltUEen) (EiBij) (UwoOntbijt). These 7 words of second part are sort of compressed into 3 or 4 words ("bijt" in the end sounds like a separate word).
Generally, I have no issue with the lady's or the gentleman's record. After all that is what may happen if native Dutch speakers speak with normal speed. (Perhaps this is also the case in other languages as well).
However this is a course for BEGINNER. That being said, it is unlikely that course team will work out a middle speed version of record. So I am afraid we have no other option but try to practice as much as we can to get the sense.
Some of my own experience:
Regarding the "wilt", it seems that the "t" in the end will not be pronounced or VERY lightly. For me, "wil" is wilt (depends on the subject, if preceded by Ik then it is wil). If I hear "t" or "te" then I assume the next word is "het/de" (also slurred so I cannot hear it clearly). If it sounds like "ten" then the next word should be "een" ("te" and "ten" on the other hand also need effort to distinguish).