I have been experimenting with Ubuntu (multiple flavors) for some time with my primary purpose being web browsing, watching netflix and online sports. The computer on which I have been experimenting this is a 6 year old Dell Precision M90 with Nvidia Quadro FX 1500M display card. The reason I mention the video card is that this card does not support full hardware based decoding of Flash and other video codecs.
Netflix depends on Silverlight DRM for playback in browsers (exception being IE 11 on Windows 8.1, where it uses HTML5). Silverlight DRM does not have a port on Linux (due to copyright issues) and hence Netflix can’t be run natively on Linux. The non-native ways of rendering Netflix on Linux are not very optimized and result in almost non-playable condition on my old laptop. If I run Netflix on Windows, the Silverlight plugin does not use hardware acceleration (due to lack of support from my video card and due to my usage of a version of Windows which is not optimized), and hence the playback is not smooth.
Flash videos currently depend on Adobe Flash player support. Adobe has stopped providing Flash player upgrades for Linux (the last version being 11.x on Linux, whereas on Windows the current version is 13.x). So on Linux we get very bad performance for Flash videos, unless you are using Chrome and Pepper Flash plugin.
I have tried Windows XP, Vista and 8.1 on my old laptop, and I get the best video performance (across Netflix and Flash) on Windows 8.1. On Windows 8.1 the CPU load is 3 times lesser when playing a full HD Flash video as compared to Windows Vista. The same with Netflix.
This basically tells us that companies are not providing us support for old operating system, and are forcing us to move to new OS. Adobe flash player 13.x is way more preformant on Windows 8.1 as compared to any of the old OS’s. HTML5 takes 50% less CPU as compared to Flash, and still Netflix only supports that in Windows 8.1 + IE 11.
So old computer + Ubuntu is really not a option for watching Netflix and Flash videos.