The video shows a series of clips of a person dancing and forming semaphore letters. In each clip, the same bigram is formed twice (for redundancy) and then there is a final pose that is not a semaphore letter. The final poses are from the Sherlock Holmes Dancing Men cipher. There are many different versions of this cipher, but the version used in the puzzle is the cipher as defined in the original story The Adventure of the Dancing Men. Also, only letters used in the text are used in the clips.
Decoding the semaphore is the easiest first step. The clips are shown in the video are in alphabetical order by semaphore bigram, so there must be another way to get an ordering. In each clip, the dancer is dancing in front of a room with a clearly visible number. (Actually, we couldn't find a single building that had all the room numbers we wanted, so we bought reflective house numbers and renumbered doors in LeConte Hall.)
|Clip||Semaphore||Dancing Man||Room number|
The first (floor) number of the rooms are sometimes repeated but the last two digits range from 01 to 12 with no repeats. Reordering the semaphore by these numbers gives the phrase SHIFT DANCING MEN BY FLOOR NO. Then, shifting the dancing men letters forward in the alphabet by the floor number and keeping the same ordering gives the phrase AWKWARD FLAIL.