091711-809-carib-whole.wmv -

Then the next number is -809. That could be a sequence number or an identifier. Maybe it's the part of a series or a specific identifier for this particular file or version.

Also, check if "809" has any special meaning. Maybe it's a batch number or project code. If unsure, it's best to note that it's an unidentified identifier. 091711-809-carib-whole.wmv

If 09 is the month (September), 17 is the day, 11 is the year, that would be September 17, 2011. That seems plausible. So the first part is the date 09/17/11. Then the next number is -809