In part 13 when Sarah Palmer (kind of) watches a black and white boxing match (and finds all her liquor bottles empty) the boxing is just the same 20 seconds or so repeating over and over. I considered this was a production short-cut we weren't meant to notice, but Lynch keeps cutting back to the screen, so I think he wanted us to know. It likely symbolizes Sarah being stuck in the past, unable to move on from the tragedies of her life.