C# helper method for parsing out links and video (Vimeo & YouTube) content

LinkParser.cs

using System;
using System.Text.RegularExpressions;

namespace DalesLab.Helpers
{
	public static class Parser
	{
		public static readonly Regex VimeoVideoRegex = new Regex(@"vimeo\.com/(?:.*#|.*/videos/)?([0-9]+)", RegexOptions.IgnoreCase | RegexOptions.Multiline);
		public static readonly Regex YoutubeVideoRegex = new Regex(@"youtu(?:\.be|be\.com)/(?:(.*)v(/|=)|(.*/)?)([a-zA-Z0-9-_]+)", RegexOptions.IgnoreCase);
		public static readonly Regex HyperlinkRegex = new Regex("http(s)?://([\\w+?\\.\\w+])+([a-zA-Z0-9\\~\\!\\@\\#\\$\\%\\^\\&\\*\\(\\)_\\-\\=\\+\\\\\\/\\?\\.\\:\\;\\'\\,]*)?", RegexOptions.IgnoreCase); //http://weblogs.asp.net/farazshahkhan/regex-to-find-url-within-text-and-make-them-as-link
		
		public static string ParseLinks(string str)
		{
			//here we pass through all of the regex
            MatchCollection HyperLinkmatches = HyperlinkRegex.Matches(str);
            foreach (Match match in HyperLinkmatches)
            {
				
				Match youtubeMatch = YoutubeVideoRegex.Match(match.Value);
				Match vimeoMatch = VimeoVideoRegex.Match(match.Value);
				
				if (youtubeMatch.Success)
				{
					var id = youtubeMatch.Groups[1].Value;
					str = str.Replace(match.Value, "<iframe id=\"ytplayer\" type=\"text/html\" width=\"640\" height=\"390\" src=\"http://www.youtube.com/embed/"+id+"\" frameborder=\"0\"/>");
				}else if (vimeoMatch.Success)
				{
					var id = vimeoMatch.Groups[1].Value;
					str = str.Replace(match.Value, "<iframe src=\"//player.vimeo.com/video/"+id+"\" width=\"WIDTH\" height=\"HEIGHT\" frameborder=\"0\" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>");
				}else
				{
					str = str.Replace(match.Value, "<a target='_blank' href='" + match.Value + "'>" + match.Value + "</a>");
				}
                
            }
			return str;	
		}
	} 
}