You're basically right; I'm not a native speaker, but the first Kanji writing of it that I could find was 馬太. I typed that in to Google and it came up as Matthew in Chinese... although this is Japanese, the two languages are strongly related so I imagine its some type of name. The characters by themselves mean 'horse' and 'big' respectively so it might be an insult of some sort?
For anyone who wants to do some searching, look up ウマタロウ, which is what is displayed in the screenshot. Also look up its hiragana form うまたろう and one of its possible kanji forms 馬太.
