models.py

Define models for all of the types you want to put in your gallery, then create a Gallery subclass that specifies which models to allow for its members.

from galleries.models import Gallery
from imagekit.models import ImageSpec
from imagekit.processors import Crop


class YouTubeVideo(models.Model):
    title = models.CharField(max_length=50)
    embed_code = models.TextField()
    thumbnail = models.ProcessedImageField([Crop(60, 60)],
                                            upload_to='gallery_posters')

class Photo(models.Model)
    title = models.CharField(max_length=50)
    description = models.CharField(max_length=255, blank=True)
    original_image = models.ImageField(upload_to='galleries')
    thumbnail = models.ImageSpec([Crop(60, 60)], image_field='original_image')


class ApartmentGallery(Gallery):

    class GalleryMeta:
        member_models = [Photo, YouTubeVideo]

The gallery class will automatically create a membership (through) model, which will be accessible at ApartmentGallery.Membership.

admin.py

from .models import ApartmentGallery
from galleries.admin import register_gallery_admin

register_gallery_admin(ApartmentGallery)

settings.py

INSTALLED_APPS = (
    'imagekit',
    ...
)

This should register you new app with our galleries models and include the thumbnail preview.