I had a customer call in this week after struggling to resolve an issue for a couple of days, Their Transaction Log file had grown to 400+GB and was filling the drive to the point that had to keep adding space to the drive to keep operations online. This was for a core internal system. There are no staff DBAs here, but plenty of very sharp sysadmins, developers, network folks, etc.
Note: I have written about the most common cause of this issue here, but this was not the resolution in this case. The embedded video is far and away number one in hits of all my SQL videos, showing just how common log file growth issues are.
I like the way Kevin does this. He frames the story, takes you through his actions, and gives you a chance to understand his troubleshooting process. Most problems become an order of magnitude easier to solve if you have a reasoned-through process (and enough practice to follow when three levels of management are staring at your screen during a crisis).