It is very hard to pick up on, it shouldn't be silent though. It's like having a "b" and a "g" together without any vowel. So it ends up that you don't hear much of the ב
אֲנִי רוֹצִים בְּגָדִים I've started looking up pronunciations on Wiktionary, as soon as you learn the sounds of the vowel points - nikkud, you can read all Hebrew words written this way. I hope that the team will consider using nikkud for all new words in the early lessons. It would be a great help for beginners, and I take it that this course is primarily for the benefit of beginners!
I can't even read nikud anyways so to me it would just be a clutter. Another thing to note is that many people are experiencing bugs where if a word has nikud they will be marked wrong if they don't use it (which you can't on mobile). I would submit that until/unless Duolingo fixes this bug, Tree 2.0 should have all nikud removed, rather than adding more, when it's already creating issues.
If you're having trouble learning the pronunciation of words I strongly encourage you to check out the companion course on Memrise. It has practically every word in the course and you can for the most part, just follow along as you go through Duolingo. The way I do it is I first do a Memrise lesson, to learn the words, and then do a Duolingo lesson. It works great!
I agree with those who do not hear the bet in בגדים. Clearly the bet and mem are labials and could get lost in each other, so I don't doubt that the pronunciation is a genuine possibility. But for a beginner course, perhaps DL could make an adjustment on this one and pronounce the bet more clearly?