The video has the added bonus of letting you hear what happens when a bobbin isn't wound properly and the end comes undone while stitching. Operator error, most likely.
Here's the finished product. Can you see the repair? Me neither and that's with contrasting thread. I've also borrowed my 5 year-old's favorite new toy, a pointer finger on a stick. I think I might have to use it instead of my seam ripper!