Can preloaded YouTube subscriptions be fetched & watched offline?

[jdbii]

In YouTube app (not 3rd party workaround) under settings there is a feature that permits preloading subscriptions when on wifi to save mobile data bandwidth. Can those videos be fetched while on wifi and viewed completely offline, or when attempting to view, is a data connection still required even though the videos have been preloaded? For instance, the YouTube app won't launch when I'm in airplane mode. Also, its not apparent to me whether or not the videos have actually been fetched and stored on my phone. Thanks.