A guy invents a way to travel through time and doesn't consider all the ways it could go wrong before he jumps into history to make some changes. No, it's not about a timeline paradox, this is about more immediate, practical considerations you should work out before you even start.
This video from Tom Ska does have some mildly NSFW language. And an unbelievable amount of "not thinking ahead." -via Geeks Are Sexy