I found that I can start a YouTube video in stock YouTube player this way:
Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(\"vnd.youtube:U79wVTdnMpw\"));
Youtube 400 network error: Turn off and on Clear data and cache
Settings applications manage applications clear data and cache
You will need to log in each time. Unfortunately I still can not post but can share comment on g+