The long shots got up in the 7th at Melton tonight and there would seem to have been less than a quarter of a unit on the First 4 (if my maths is good) so $3541 of the $5382 pool jackpotted.
https://www.tab.com.au/racing/2016-05-27/MELTON/MLT/H/7
Race 8 comes next and we see a pool of $20k for the First 4. On top of the jackpot, I make that to be $11k more than it would have attracted.
https://www.tab.com.au/racing/2016-05-27/MELTON/MLT/H/8
Everybody / pros love a crack at 'bonus' money
(I do always have a crack at Powerball after it jackpots a couple of times)