diff --git a/listdict.py b/listdict.py
new file mode 100644
index 0000000..17da94a
--- /dev/null
+++ b/listdict.py
@@ -0,0 +1,32 @@
+import random
+
+class ListDict(object):
+    def __init__(self):
+        self.item_to_position = {}
+        self.items = []
+
+    def add_item(self, item):
+        if item in self.item_to_position:
+            return
+        self.items.append(item)
+        self.item_to_position[item] = len(self.items)-1
+
+    def remove_item(self, item):
+        position = self.item_to_position.pop(item)
+        last_item = self.items.pop()
+        if position != len(self.items):
+            self.items[position] = last_item
+            self.item_to_position[last_item] = position
+
+    def choose_random_item(self):
+        return random.choice(self.items)
+
+    def __contains__(self, item):
+        return item in self.item_to_position
+
+    def __iter__(self):
+        return iter(self.items)
+
+    def length(self):
+        return len(self.items)
+
diff --git a/mt_clockwheel.py b/mt_clockwheel.py
index eb9523d..d8c4bff 100644
--- a/mt_clockwheel.py
+++ b/mt_clockwheel.py
@@ -1,6 +1,8 @@
 import argparse
 import datetime
+from glob import glob
 import json
+from listdict import ListDict
 import os
 
 # globals
@@ -11,9 +13,11 @@ verbose = False
 from_date = datetime.date.today()
 to_date = datetime.date.today()
 playlist_duration = 6 * 60 * 60 # six hours, in seconds
+mediadirs = ListDict()
 
 def main():
     parse_config()
+    get_media_dirs(mediadir)
     for single_date in daterange(from_date, to_date):
         if verbose:
             print("Processing date", single_date)
@@ -69,6 +73,19 @@ def parse_config():
         print("from_date:", from_date)
         print("to_date:", to_date)
 
+def get_media_dirs(rootdir):
+    for file in os.listdir(rootdir):
+        if file == "Commercials":
+            pass
+        elif file == "Television":
+            get_media_dirs(os.path.join(rootdir, file))
+        else:
+            d = os.path.join(rootdir, file)
+            if os.path.isdir(d):
+                if verbose:
+                    print("adding " + d + " to media dirs")
+                mediadirs.add_item(d)
+
 def build_day(this_date):
     d = {} # empty dict that will become our JSON output
 
@@ -77,11 +94,14 @@ def build_day(this_date):
     d["program"] = [] # empty list to populate with programs
 
     total_time = 0
+    get_commercial = False
 
     while total_time < playlist_duration:
-        entry, length = get_playlist_entry()
+        entry, length = get_playlist_entry(get_commercial)
         d["program"].append(entry)
         total_time += length
+        if length > 0:
+            get_commercial = not get_commercial
         if verbose:
             print('  added program:', json.dumps(entry), length)
 
@@ -93,14 +113,34 @@ def build_day(this_date):
 
     return playlist
 
-def get_playlist_entry():
+def get_playlist_entry(get_commercial):
+    exts = ['*.mp4', '*.webm', '*.mov']
+    entry_dir = mediadir + '/Commercials' if get_commercial else mediadirs.choose_random_item()
+
+    media_files = ListDict()
+
+    found_media = [f for ext in exts
+                   for f in glob(os.path.join(entry_dir, '**', ext), recursive=True)]
+
+    for d in found_media:
+        media_files.add_item(d)
+
+    this_file = media_files.choose_random_item() if media_files.length() > 0 else ""
+    if this_file == "":
+        return "", 0 # get out of this oopsie situation and try again
+
+    # TODO: ffprobe file for duration
+
     entry = {
         "in": 0,
         "out": 300,
         "duration": 300,
-        "source": "test.mp4"
+        "source": this_file
     }
 
+    if get_commercial:
+        entry["category"] = "advertisement"
+
     length = entry["duration"]
 
     return entry, length