[debaserab2]

Another school of thought is that it doesn't matter if it's the responsibility of the browser because the customer perception will be that your website does not work for them.

If a mechanism exists to prevent your customer from perceiving this, as a business the smart decision is going to be to use it.

[pmontra]

Partly true, because if they try with another browser and get a good result they'll blame the browser and not the website. In this case, they'll probably say the the new Firefox broke YouTube. See one of the comments at www.pclinuxos.com/forum/index.php?topic=135323.0

"i'm getting a lot of corrupt unsupported browser when accessing video on other sites, so i'm using chrome. i can't figure out if it's flash or firefox but i'm tired of opening the hood, i'm done with FF for now"

Most of them looked for a workaround and spoofed the user agent, but they are the kind of people that fiddle with settings. Normal users probably either don't notice or change browser.