Bandwidth required for high quality desktop sharing?

I'm researching desktop sharing products for the possibility of using them to train people to play computer games. To make this practical it's pretty important we get a frame rate of at least 20 fps (these are slow puzzle games not fps or anything).

I'm trying to get an idea of what kind of system requirements this would need for the users. What kind of upload and download speeds they'd need?

Also are there any products or services that do a better job of compressing this stuff then others?

I don't need a list of services that offer desktop sharing as I've already don that research. I just need advice on bandwidth requirements and any service that gives a better performance to bandwidth payoff (assume this would be done with compression).