Browsers don’t redistribute the content. That’s a crucial difference, much like you can video tape a broadcast and fast forward through the ads at home, but not if you run a pub.

I haven't looked at the code, but maybe this site doesn't redistribute anything, either.

And just because something's executing on the server side, that really shouldn't necessarily change the legality of it. (Hell, maybe Safari or Chrome look like they're doing it locally and tunnel data through a cache server.)