I am trying to get list of videos uploaded on my YouTube channel using following
https://www.googleapis.com/youtube/v3/search?part=snippet&channelId{MY_CHANNEL_
This is not exactly what you are asking but I will share my experience.
I had a similar situation a couple of months ago. Seaching on line I got to the conclusion that the YouTube api option for Android just doesn't work. I ended up with a more convenient solution for my development:
I got a YT api key for a website and bound it to the corresponding domain.
I Created a php file that gets the playlist from youtube twice a day using curl and cron job setup on the server. The playlist file in json format is then written to the web server (refreshed twice a day).
The Android app connects to my server intead of YTs and get the "cached" json play list from there.
This option drastically reduces the impact on the quota consumption because all the hits to the playlist go to the website.
If you are interested in this option I can share the php used for getting the play list.
I had the same problem, just regenerate another key and restrict it again with the package name and SHA1 from your Android Studio. It wasn't working with the old key regenerating the key and restricting it again worked for me.
Without looking at your API Console settings, I cannot say for sure. But from looking at the HTTP response, it looks like your IP address might be blocked by the Google authorization server. Hence, it is sending you back an unauthorized request HTTP status code 403.
Go to your API Console and select the None radio button from under the Key restrictions section. Then try again. It should work.