Inviting non registered users to a Vidyo meeting can be easily done in 4 steps:
1) Log in to the VidyoDesktop client
2) Click on the meeting name. Note that by default you will control your own personal room. If you are owner of more than one room, you will see the list of rooms that you own and you will need to choose one.
3) Click on Invite by Mail or on Room Settings then copy&paste the room link into your preferred email client and send it to the non registered participants you want to invite.
4) When clicking on the link, the invited participant will only need to enter a random Guest Name and click on Join. He will then be proposed to the Vidyo web client, or download the desktop client if not yet installed, and once done will automatically be connected to the Vidyo room.
If you are creating Vidyo meetings through Indico, just send the non registered users the auto-join URL generated after the meeting creation. The invited participant will just need to execute step 4)