[Demongornot]

I tested your 2 codes and mine and I got to the conclusion that mine and your second one does the same thing but your first on get trouble when the "DownloadHost" differ from what is in the url.

Using this code :
Trigger : Downloadlist Contextmenu Button Pressed

myDownloadlistSelection = dlSelection;
if (myDownloadlistSelection.isLinkContext() == true) {
    var myDownloadLink = myDownloadlistSelection.getContextLink();

    var rAr = Discombobulator(myDownloadLink.getPluginURL(), myDownloadLink.getProperty("LINKDUPEID"));
    var host = myDownloadLink.getDownloadHost();
    var url = myDownloadLink.getProperty("LINKDUPEID") || myDownloadLink.getPluginURL();
    var rAr1 = url.replace(new RegExp(".+:\/\/.*" + host + "/"), "").replace(/.+:\/\//, "");
    var rAr2 = url.replace(/(^(https?|ftp):\/\/[^\/]+\/)/, "").replace(/.+:\/\//, "");
    var nl = getEnvironment().getNewLine();
    var sep = nl + "_______________________________" + nl;
    var t = ["Demongornot's :" + nl, "mgpai's 1 :" + nl, "mgpai's 2 :" + nl, "Host :" + nl, "LINKDUPEID or Plugin URL :" + nl];
    alert(t[0] + rAr + sep + t[1] + rAr1 + sep + t[2] + rAr2 + sep + t[3] + host + sep + t[4] + url);
}

function Discombobulator(pluginURL, LINKDUPEID) {
    var shortURL;
    if (LINKDUPEID == null) {
        shortURL = pluginURL;
    } else {
        shortURL = LINKDUPEID.toString();
    }
    var authority = shortURL.indexOf('://');
    if (authority < 0) return shortURL;
    var shorterURL = shortURL.substring(authority + ('://').length);
    if (turboEncabulator(shortURL.substring(0, authority))) return shorterURL.substring(shorterURL.indexOf('/') + 1);
    return shorterURL;
}

function turboEncabulator(bit) {
    var protocols = ['http', 'https', 'ftp'];
    if (protocols.indexOf(bit.toLowerCase()) >= 0) return true;
    return false;
}

I got this :

Demongornot's :
embed/xxxx
_______________________________
mgpai's 1 :
streamango.com/embed/xxxx
_______________________________
mgpai's 2 :
embed/xxxx
_______________________________
Host :
fruithosts.net
_______________________________
LINKDUPEID or Plugin URL :
(protocol)streamango.com/embed/xxxx

As the host name and url don't match, other than that your first script work in any cases when there are subdomains before or after AFAIK.