Not for nothing, ASL is a language, not English with hand gestures. This is as useful as showing a wall poster of the Greek alphabet and hoping to communicate with everyone in Greece.
Sure, it's useful for spelling your name, but that is not language, your name is just the noise someone needs to make to get your attention.
I opened this to say that it wasn't really a cool guide, just an alphabet, but I don't think it was trying to claim you could produce the language by knowing some letters. In fact, knowing any language's alphabet alone doesn't confer the ability to communicate in that language. You could vaguely make a go of it with languages that rely heavily on logographs like Chinese, but even that won't really get you very far.
Actually less useful. Most of the letters are shown as the viewer would see them, but some are from the perspective of the signer, with no indication which is which.
