It's not a word in any language according to Google Translate and Wiktionary. Nor is it an English word according to Opera Spell checker or my hardback copy of Chambers Dictionary.
However, once Googled the first hit for @migueltarga is a Twitter page. One of the lower hits is on Google's support forums asking what exactly the problem is, apparently it's a Brazilian, or group of Brazilian, hackers editing the names of frequently viewed videos for attention.
Why does migueltarga have http:///alert'XSS' as his "website"? Lol.
Probably because he's hacking his own website (Twitter?) in order to get malicious scripts running. Intriguingly there was recently an XSS outbreak on social networking sites that opened up pr0n windows by hovering over comments using a JS script.
Finally the last part of the title is Portuguese for "Loved you video". (Remember the Latin amo, because it helps you recognise the word love in just about every European language. )
So, I got it figured out. Someone is going around using XSS to hack into youtube to change the titles of popular videos to
Exactly. XSS is just away to change data which should be confidential and uneditable to anyone in the public. These Lady Gaga-loving hackers found away around it, and are changing the titles to their names and saying how they loved the video. The person who uploaded the video simply has to change the name and the databases have all the same data they did prior to the hack.
Doing things like this normally gets you a brief period of fame amongst the hacking community. Hackers also simply enjoy doing this stuff for the sake of it.