On Firefox/Mac, the numbers on the results page go 1-9 and then typically pick up at 31. No results are dropped, but this is disconcerting.

To have auto-scrolling enabled at startup, I edited the script as follows:

Changed the inital setting for this variable from -1 to 1:
var Enable = 1;

Moved these three lines from the function dblClickEvents to the ending initialization block:
init_autopager();
insertLoadingText();
watch_scroll();
following the statement:
document.body.addEventListener etc.