In the far off time when video conferencing first arrived I remember an Annual Budget meeting (quite competitive) held by the parent company in the USA with people calling in from London, Paris, Oslo, Cairo etc.
All was trialed and worked well.
On THE DAY the first guy up was the local guy in the office in Houston. All went swimmingly but as he stepped down he somehow kicked a box of tricks and removed the video element - leaving everyone else to "present" using voice only. Oddly enough he was the only guy who got 100% of the cash he was asking for - tho' to his dying day he swore it was accidental...............