yt-direct-lite-android | reference implementation for an Android OS application

I discovered YouTube Direct Lite (Android/Java) on GitHub (https://github.com/youtube/yt-direct-lite-android) as a good example of how to allow users to upload a video to your YouTube playlist. I've got it to work successfully in debug and release apk mode on Android 5.1.1 on Nexus 4 and Android 4.2.2. on Galaxy Tab 7. However, I get a "Connection to Play Services failed" message on installing to Android 7.0 on LG4. "Unfortunately, I-Witness (renamed app) Uploader has stopped" is the message before the app crashes, when I select my log-in account.

On initially importing the code from git, Android Studio 3.01 showed some outdated libraries, which I updated, and found a cure for a httprequest/httpclient error caused by one of said outdated libs. The biggest issues revolved around 'com.google.android.gms:play-services-auth' and 'com.google.android.gms:play-services-plus' which were at 7.8 in the original example.

Android Studio recommended update to the current 11.8 but when I did many 'red underlines of death' showed up in the code and so I was successful using 'com.google.android.gms:play-services-plus:9.0.0' and com.google.android.gms:play-services-auth:9.0.0.

Specifically, 11.8 causes a conflict with the below external libraries related to firebase, which I don't understand since firebase is not implemented in the project:

I am able to play videos using the YouTube Player API 1.2.2 for Android. However, users always see pre-roll ads even if they have a YouTube Red subscription. I could not find any documentation surrounding video playback as a specific YouTube user, in order to take advantage of a YouTube Red subscription, which disables ads.

The javadoc for YouTubePlayerSupportFragment.initialize() says:

public void initialize (String developerKey, YouTubePlayer.OnInitializedListener listener)

Initialize a YouTubePlayer, which can be used to play videos and control video playback. One of the callbacks in listener will be invoked when the initialization succeeds or fails.

Parameters

developerKey A valid API key that is enabled to use the YouTube Data API v3 service. To generate a new key, visit the Google Developers Console.
listener The callbacks that will be invoked when the initialization succeeds or fails.

So it takes an API key, rather than a user's OAuth credentials. Is there any way to pass the OAuth credentials instead, to play a video as a specific user?

I saw this example app: https://github.com/youtube/yt-direct-lite-android -- It shows an example of using OAuth 2.0 to upload videos, but the playback uses a simple API key only.