He did say that properly implemented encryption works. That does indeed mean that with properly implemented crypto, without the key, ciphertexts are unreadable. But the video never mentioned Snowden also said the NSA routinely bypasses encryption by hacking the endpoints. The video did touch on the topic of hacking but it focused on backdooring standards. That is again no reason to throw in the towel, you should be protecting yourself from other threat actors no matter what the NSA does.