It is common for presenters and panelists to tape their performance. Doing so works well for both reviewing to moment to refine your presentation skills and, as a download for your website visitors.
But if you would like to really get a look at how well you did -- point a camera at the audience.
Of course you need to let the audience know they have a camera pointed their way -- and in true Pavlovian style* the audience, at least for a little while, will appear to be incredibly attentive and interested. But skip toward the end of your recording, when most of the audience has forgotten they are on tape, and you will witness their true reaction to your presentation.
You may be wonderfully surprised to see an audience that is really into your performance, or, you might witness something different. In either case you will know a truth.
Do you dare to try it?
* NOTE: Ivan Pavlov surmised that the simple act of letting factory workers know their workplace is being studied increased overall productivity.