I like the "you should have seen that Duo" option.
Could you also say je zou die vogel moeten gezien hebben! instead, or does the word order have to be this?
you can use both
Why was I marked wrong for using "gezien" with "jullie", when it can be used with "jij": "jullie zouden die vogel moeten hebben gezien!" DL marked me wrong for using "jullie...gezien", and put "jij" in place of "jullie". ?!?
in my opinion jullie should also be accepted
Dutchgrammar.com gives "had moeten +infinitive", not "zou moeten hebben +past participle", as the translation of "should have"...
So this sentence would be:
Je had die vogel moeten zien!
Is this correct?
Yes, that's what I wrote (and it's correct). They're both good options.
Why is "JIJ zou die vogel moeten hebben gezien" not accepted?
It is, only not for a listening exercise due to the difference in pronunciation.
I don't think it was for a listening exercise though...
Why is "Je ZOU die vogel moeten zien" not accepted? I thought this whole chapter was on zou...
That's a different tense: 'You should see that bird'.
'Je zou die vogel moeten hebben gezien' = 'You should have seen that bird'