Crie dicionários a partir de seus elementos de formulário.
incdict = {'releasedate__gte': datetime.datetime(2000, 1, 1)}
excdict = {'genre': 'Horror'}
moviequery = Movie.objects.filter(**incdict).exclude(**excdict)
incdict = {'releasedate__gte': datetime.datetime(2000, 1, 1)}
excdict = {'genre': 'Horror'}
moviequery = Movie.objects.filter(**incdict).exclude(**excdict)