Here is a free option: http://www.freeconferencecall.com. It allows you to do teleconferences as well as video meetings where you can share the screen. If I remember correctly, the participant does not have to download anything to participate. One of the things some people have issues with is downloading software, whether it is Skype, Zoom or Join.me.
With freeconferencecall.com, you can have up to 5 video feeds and up to 1,000 participants. I haven’t tested it with that many, but it is cool to know that there is that capability.