My guess is that each such page is constructed dynamically, that is, for one specific user from a recommendation engine based on the most recent data YouTube has on that user. When I mentioned elsewhere in this thread "If click around enough at YouTube ...", that was very short for something like a guess that if a YouTube user watches a few movies and that is mostly what they do watch at YouTube, then some YouTube recommendation engine constructs for that user then a page of just movies. But that page and its URL may be valid only for a short time: So, saving the URL for later or giving it to someone else won't be useful.
Can imagine a horror movie: Joe frequently goes to the university library for applied math books but today happens to want a certain book on ancient Greek history. So, as Joe walks down an isle in the history section, the books notice that it is Joe and all change themselves to applied math! Poor Joe can't find his book on ancient Greek history!
Can imagine a horror movie: Joe frequently goes to the university library for applied math books but today happens to want a certain book on ancient Greek history. So, as Joe walks down an isle in the history section, the books notice that it is Joe and all change themselves to applied math! Poor Joe can't find his book on ancient Greek history!