Remove old YouTube versions

Change-Id: I31145c327f1e9893166fc8e7f5c25ee8241395a8
diff --git a/tools/run_on_app.py b/tools/run_on_app.py
index 60cd4f1..c775aa0 100755
--- a/tools/run_on_app.py
+++ b/tools/run_on_app.py
@@ -396,7 +396,7 @@
     version = options.version or '20180926'
     data = nest_data
   elif options.app == 'youtube':
-    version = options.version or '12.22'
+    version = options.version or youtube_data.LATEST_VERSION
     data = youtube_data
   elif options.app == 'chrome':
     version = options.version or '180917'