Update payload information for a channel

Hi everyone!

Can anybody clarify COLIBRI ‘5.2 Focus updates payload information for a channel’,
See https://xmpp.org/extensions/xep-0340.html

What are the possible uses for such requests?

Is it possible a video conference between 3 participants where,
for example, two of them have VP8 payload id=100 and the third id=96?

Thanks.