I think point 3 cannot be overstated. Iconic talks can be hugely informative or simple and brilliant in their execution. Two that come to mind and I regularly recommend to people are:
That Mike Monteiro video literally changed my life, helping me go from charging $15/hr for PHP "development" (sigh) to charging real money and getting real checks.
Wat is a great talk two, they're probably my top 2 talk videos.
