In the video everything seems fine with the villager spawner
I think it might be just moving behind the number, which sometimes may look like it stopped, so don't worry about that. Maybe make the number smaller, or the bar larger, so you always see it moving.
The only game I played like yours was the original plants vs zombies, and another game which I don't remember the name of.
I don't know if you are going for your own spin on it, or you would like to make it more like plants vs zombies.