These aren't actually Half-Life 3 leaks. I watched the video. He says everything in the video is about leaks and speculation will be marked as such. But there is nothing that points the files being Half-Life 3 related. He speculates that its about Half-Life 3 (without marking it as speculation).
So no, this is either misleading in order to get more clicks and viewer, or in best case just wishful thinking. There is absolutely nothing that makes this a Half-Life 3 leak, this is just another speculation that Valve would work on the game. You know in the past years, how often Tyler was wrong with his own speculation...