You DO need Adobe's Flash if you currently wish to view a great deal of the video on the web regardless of the hardware (or OS) you're using to view it.
Not necesarily true. Youtube, among others, would display movies in H.264 (proprietary crap from the MPAA) and Ogg (free software) under HTML5.
The real issue is that Apple can't close up their products as long as there is flash, because it works as a bypass to run stuff on the iphony and ipaad.