Quick UserScript to add a link to the highest quality video stream below the video.

betterplayer.user.js

// ==UserScript==
// @name ExternalPlayer
// @description Adds a link to show the video in an external player.
// @include http*://www.youtube.com/watch*
// ==/UserScript==
var playerparent = document.getElementById("player");
var newplayer = document.createElement("a"); 
newplayer.style.position = "relative";
newplayer.style.padding = "20px";
newplayer.style.top = "10px";
newplayer.style.zIndex = "2";
playerparent.appendChild(newplayer);
for (i = 0; i < playerparent.children.length; i++)
{
	if (playerparent.children[i].nodeName == "SCRIPT")
	{
		var streammap = playerparent.children[i].innerHTML.match("stream_map\": \"(.*?)?\"");
		if (streammap == null)
		{
			continue;
		} else {
			var maparray = streammap[0].replace(/\\u0026/g, "&").substring(14).split(",");
			//First ID is best quality on all videos I've seen
			var metadata = maparray[0].split("&");
			for (i = 0; i < metadata.length; i++)
			{
				if (metadata[i].substring(0, 4) == "url=")
				{
					newplayer.href = decodeURIComponent(metadata[i].substring(4));
				}
				else if (metadata[i].substring(0, 8) == "quality=")
				{
					newplayer.innerHTML = metadata[i].substring(8).toUpperCase() + " (External Player)";
				}
			}
			break;
		}
	}
}