Your issue is interesting - Monastery just gets the current time and then sets the time to 23:59:59.999 for when the timer resets, so I suspect that the issue lies in timezones. If you feel like helping me out to fix this: Press ctrl-shift-j and then scroll up until you find a comment along the lines of "Hourglass expires [number]" - tell me what time it is wherever you are and what number it is.
As for your feature requests - eventually, I hope to implement those as well. It'd certainly be useful for Youtube watching, at least for me.