I find AnyMeeting good for training clients, you can hold a meeting with a large group of people via email invite.
The client does not have to download any software which minimizes the time it takes to start and get everyone going.
It does lack in high end video quality and there are better packages available.
Other than that it can get a little pricey but there is a free version available.
Online web conferencing.
-via Capterra