If you are unfamiliar with what back channeling is, take a look at this link http://net.educause.edu/ir/library/pdf/eli7057.pdf. I see many benefits in using back channeling to allow questions to be answered that might not be addressed by a speaker/presenter. It allows the shy student to be able to feel more confident in question asking, it allows the thought of the meetings to go deeper for those already familiar with the topic, as well as serving as a way to answer the questions of those that feel "this is all Greek to me" because they can communicate with their peers immediately and get caught up in the conversation.
All that being said, lately I have seen and been on the receiving side of poor digital citizenship skills. An inconsiderate backchannel participate has great power with this tool. When things are said in an attacking nature or judgmental view, backchanneling can go from being a resource with positive results to making the speaker want to ball up in a corner sucking their thumb in the fetal position.
Since no one wants to see that, here is my attempt at some suggested Rules of Engagement for BackChanneling. Some of these may seem like common sense, but after my week I feel the need to make this as simplified as possible.
1. Make sure whatever you would type in the thread is something you would say face to face to that speaker.
2. Passionate feelings are not bad but make sure if you disagree you are doing it in a constructive way. Constructive criticism helps us grow, it is still painful, but by using BackChanneling we are saying "Hey, I would like your thoughts on this." Be sure not to ATTACK THE SPEAKER AND FOCUS ON THE IDEAS BEING PRESENTED.
3. Use a moderator in case things get off track. This does not have to be prior planned. Just ask someone if they would be willing to "police" the conversation and gently guide the responses back to the appropriate topics. Not all speakers follow the BackChanneling while they speak, so this can be a great help to the speaker.
4. Resist the urge to turn a thought into an ongoing conversation that becomes silly, stay professional. This becomes a distraction to others and shows disrespect to the speaker by your "hijacking" of the event.
5. If you adamantly disagree with something that is being said, think of the immortal words of Thumper, "If you can\'t say something nice...don\'t say nothing at all." Save your thoughts for after the presentation and go speak directly to the speaker. This allows facial expressions and the emotion behind the thoughts to be expressed.