Learn English – “Introduce person to object” or “introduce object to person”

curtailed, lost, ruined, squandered, nullified, wasted, rendered ineffective...

The sentence would read better as "The movie won several awards, among them Best Documentary and Best Short Film."

As it is now, which would have to be followed by a verb (in this scenario, were), and the result is a comparatively awkward sentence: "The movie won several awards, among which were Best Documentary and Best Short Film."

I think the reason for this is that which is a relative pronoun used to introduce a relative clause. Clauses must have verbs, so in your original example the sentence feels unfinished: "among which the best documentary and best short film..." Were what? We need an action.

Them, on the other hand, is a simple pronoun, so it doesn't create a relative clause like which does. Therefore, we can end the sentence with the appositive phrase, "among them Best Documentary and Best Short Film."