+1 for the conference slides that you can't see. The other along that line is the cut back and forth between the speaker and the interactive session they are showing things in. Unless the speaker is doing a wardrobe change, I don't need to see them again.

And finally, if you are going to live demo, please, please learn to type. Mavis Beacon should be your best friend. Nothing like watching people stumble around on the keyboard for 5 mins to get printf("Hello World\n"); on the screen