At 0:02, a fuzzy black shape appears in the video's upper left corner. Then the clip is replayed at slower speed, and the figure is shown again at 0:09.
"This video was sent to us from one of our viewers whose username is couch potato," reads the caption.
Couch potato writes, "I was long boarding near Lake Tahoe and recording some footage testing out my new GoPro Hero3+. I didn't notice the bigfoot like creature until I got home several days later and watched my videos."