Quarantine - S5-E4
Visible crew/equipment: When Lister wipes down the biohazard cabinet, a boom mic can be seen in the top right of the screen. Also, just before the camera moves past the pillar, the entire microphone and arm can be glimpsed. (00:05:00)
Quarantine - S5-E4
Visible crew/equipment: When the Cat tries to attack Rimmer in Quarantine, a boom mic can be seen at the top of the screen. (00:16:45)
Quarantine - S5-E4
Visible crew/equipment: When Rimmer asks the crew if they had forgotten Red Dwarf could only sustain one hologram, it shows a shot of the rest of the crew who say nothing. At the top of the screen, a boom mic can be seen. (00:03:00)
Answer: The cello is a large four-stringed instrument, which, when it is played, stands vertically on the floor between the player's legs (assuming they are seated). If it is to grow as large as the other instuments mentioned will, it would require a rather unseemly lack of femininity to be able to encompass it with the legs.
Rooster of Doom