Found a way to get passed this.
I used GoogleAuthorizationCodeFlow instead. this is what it turned out to look like:
ClientSecrets secrets = new ClientSecrets()
{
ClientId = CLIENT_ID,
ClientSecret = CLIENT_SECRET
};
var token = new TokenResponse { RefreshToken = REFRESH_TOKEN };
var credentials = new UserCredential(new GoogleAuthorizationCodeFlow(
new GoogleAuthorizationCodeFlow.Initializer
{
ClientSecrets = secrets
}),
"user",
token);
var service = new YouTubeService(new BaseClientService.Initializer()
{
HttpClientInitializer = credentials,
ApplicationName = "TestProject"
});