// For embed link:
var url = @"https://www.youtube.com/watch?v=6QlW4m9xVZY";
var uri = new Uri(url);
// you can check host here => uri.Host <= "www.youtube.com"
var query = HttpUtility.ParseQueryString(uri.Query);
var videoId = query["v"];
// videoId = 6QlW4m9xVZY
// For youtube/watch link:
var url = "http://youtu.be/AAAAAAAAA09";
var uri = new Uri(url);
var videoid = uri.Segments.Last(); // AAAAAAAAA09
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Source: https://stackoverflow.com/questions/39777659/extract-the-video-id-from-youtube-url-in-net
Answer by: tym32167