The latest videos on http://wrla.ch/eideticker/dashboard/#/nytimes-scrolling/uniqueframes show a dialog coming up. This likely prevents additional touch events from reaching the page, and likely throws off the results.
I thought this was fixed with: https://github.com/mozilla/eideticker/commit/55d63960dc0a5090cee00fe917a851db082ee0fd I guess it's possible that somehow the drag event is being misinterpreted as a long touch in some cases, though I thought that was only happening before because the "touch down" time was not being correctly set. The right solution might just be to make events a bit more deterministic (see bug 749472), which would make this edge case (almost?) impossible to trigger, as well as make the results more predictable.
We've switched the event handling code to use orangutan here, which is more deterministic than monkeyrunner in the order/timing of events, etc. As far as I know we haven't seen this problem since I did.