Using flash on the Mac has been for sometime quite painful. Even a trivial flash app will bump the CPU up, and most times causing the fans to kick into overdrive.
On a Macbook Air, it is quite painful to listen to the machine screaming because someone sent me a link to some cat doing something funny.
I’ve noticed since getting the iPad there is very little if any website that requires me to have flash to view it. So I removed Flash from my Mac to see how I get on (as well as Silverlight).
Overall I’ve found that I don’t need it. Youtube works for the most part. Some videos fail to load, although not always due to the video.
Some sites that I found working on the iPad failed horribly with “You need Flash” messages. Changing the USER-Agent string to mimic an iPad, these sites worked again by switching over to HTML5.
From the Silverlight end, only Netflix is the site I’ve come across that becomes non-functional.
So from my experience, Flash is not a needed to enjoy internet media.