It is hilarious, especially when Freddie keeps talking after his mouth has stopped - bad lip-sync! Apparently someone made a "funny" that cracked them up - I wonder what was said.
Later: Watched again. I wonder what Roger said.
I had to look up the history of One Vision in Queen Complete Works by Georg Purvis and here is an excerpt:
"The video finds the band at work and play in Musicland, and is certainly not as intriguing or captiviating as the first three videos from The works. However, what does capture the imagination is the 'In The Studio' portion of The Magic Years (subsequently released on The Greatest Video Hits 2 DVD) which shows the genesis of the song, from birth to completion. There are fluffed notes, arguments and general camaraderie (several lines for the song, deleted or not even considered, have been collected onto various bootlegs as 'Fun Vision', including the hilarious improvisation, 'One dump, one turd, two tits, John Deacon!'), as well as an interesting segment of Roger, Brian and Freddie mulling over the lyric to get it just right. (possibly the clip that was posted here) It's obvious that the band is hamming it up, but it's fascinating footage. The only thing that's lamentable is that Queen didn't do it more often."