Had I been sailing GE, I would have simply eased the main, that, imo, would have slowed me down enough to avoid the collision.
At time 0:14, Artemis passes head-to-wind. I see Groupe Edmond bearing away at 0:15, and I see the mainsail eased at 0:16. Both actions were taken while Team Artemis was the keep-clear boat.
Am I right in assuming that you don't have to slow down even if it is the only way to avoid a collision?
No. Rule 14 requires all boats to avoid contact if reasonably possible. Slowing down constitutes "avoiding action", and is a reasonable one to take. If a right-of-way boat maintains course but slows down to avoid a give-way boat, then the give way boat does not keep clear.
Regards,
Eric