It sounds as though the speaker is saying the "i" of vīnum (long i) and the "i's" of bibimus (both short) in the same way.
But I think we can know they were different, given the different outcomes of "wine" and "to drink" in Italian. (Isn't the drink verb formed with "e" ?)
Maybe it's been re-recorded. I'm hearing
weenum roobrum bibimus
which is actually pretty reasonable for
Vīnum rubrum bibimus.
Not quite correct, but better than most of the speakers in this course. (E.g. in "rubrum" the "u" in the first syllable and the "u" in the second syllable should be pronounced more like the "u" in the English word "put".)