I apply this regex in Regulator to the file zipped http://depositfiles.com/files/ipowahlh5
Why does "Header" group contains 11111111111111 in it? It's supposed to stop at the first </tr>.
No, look at this part of your regex:
When you have matched your first "</tr>", you tell the regex engine you only want white space characters to come in between that "</tr>" and the the next "<tr", yet there is "11111111111111" in between the first "</tr>" and the second "<tr". Besides, the second "<tr" is followed directly by a ">" making this part of your regex fail as well:
since you defined there should be at least one non '>' character after it ([^>]+).