To illustrate the query expressions, let's create the viral video detail view and plug it into the URL configuration, as follows:

1. Create the viral_video_detail view in views.py, as follows:

# viral_videos/views.py 
import datetime, logging

from django.conf import settings
from django.db import models
from django.shortcuts import render, get_object_or_404

from .models import ViralVideo

POPULAR_FROM = getattr(
    settings, "VIRAL_VIDEOS_POPULAR_FROM", 500
)

logger = logging.getLogger(__name__)


def viral_video_detail(request, pk):
    yesterday = datetime.date.today() - datetime.timedelta(days=1)

    qs = ViralVideo.objects.annotate(
        total_views=models.F("authenticated_views") +
                          models.F("anonymous_views"),
        label=models.Case(
            models.When(total_views__gt=POPULAR_FROM,
                        then=models.Value("popular")),
            models.When(created__gt=yesterday,
                        then=models.Value("new")),
            default=models.Value("cool"),
            output_field=models.CharField()))

    # DEBUG: check the SQL query that Django ORM generates
    logger.debug(qs.query)

    qs = qs.filter(pk=pk)
    if request.user.is_authenticated:
        qs.update(authenticated_views=models.F(
            "authenticated_views") + 1)
    else:
        qs.update(anonymous_views=models.F(
            "anonymous_views") + 1)

    video = get_object_or_404(qs)

    return render(request,
                  "viral_videos/viral_video_detail.html",
                  {'video': video})

2. Define the URL configuration for the app, shown as follows:

# viral_videos/urls.py
from django.urls import path

from .views import viral_video_detail

urlpatterns = [
    path('<int:pk>/', viral_video_detail,
         name='viral-video-detail'),
]

3. Include the URL configuration of the app in the project's root URL configuration,
   as follows:

# project/urls.py
from django.urls import include, path

urlpatterns = [
    # ...
    path('videos/', include('viral_videos.urls')),
]

4. Create a template for the viral_video_detail view, as follows:

{# templates/viral_videos/viral_video_detail.html #}
{% extends "base.html" %}
{% load i18n %}

{% block content %}
    <h1>{{ video.title }}
        <span class="badge">{{ video.label }}</span>
    </h1>
    <div>{{ video.embed_code|safe }}</div>
    <div>
        <h2>{% trans "Impressions" %}</h2>
        <ul>
            <li>{% trans "Authenticated views" %}:
                {{ video.authenticated_views }}</li>
            <li>{% trans "Anonymous views" %}:
                {{ video.anonymous_views }}</li>
            <li>{% trans "Total views" %}:
                {{ video.total_views }}</li>
        </ul>
    </div>
{% endblock %}

5. Set up administration for the viral_videos app, as follows, and add some videos to the database when you are finished:

# viral_videos/admin.py
from django.contrib import admin

from .models import ViralVideo

admin.site.register(ViralVideo)