At least they don't have to pay for their own hosting now, to show off their video archive!
You need to have internet access (youtube is a streaming website remember?) and these are not free for some reason.
And each time you visit youtube you're making google money by way of advertisement (and giving away some personal info), of which a portion can go back to the uploader.
If being pedantic, you also forgot to mention that using the internet requires purchasing or generating your own electricity, plus the cost to buy or rent a device with which to access the internet.
In case you weren't being pedantic, what the other commenter meant by 'free' was most likely meant to be interpreted the same way as this ‘can be accessed widely at no additional montary expense than simply loading the YouTube homepage'