The point of this website is that the server signs the timestamp. It's more than just a QR code with a time and date, it has some actual verification code.
It always only proves that it wasn't taken before a certain date.
You can then also prove "not after" by timestamping the picture (having it signed by a RFC3161 timestamping authority or putting a hash on the blockchain).
Using info from the the block is safer as you don't need to trust the host of the system.
The point (like showing a newspaper) is to prove the image / video was taken no earlier than that time.
That thought does does cast an additional possible funny interpretation on a photo I took of the adjacent street newspaper vending boxes of the two major Boston papers one day. The Boston Globe main headline was of a serious major news event. The Boston Globe above the fold was mostly filled with a photo of some political or sports figure, and a lowbrow muckraking headline about them. A funny (highly implausible) theory is that the Herald editor/publisher had needed to determine the front page for a paper issue, days or more into the future, such as for faking proof-of-life on/after a date, and then had to run that front page. :)
Nothing, which is amusing irony.
the website has the exact same problem that you pointed out for the blockchain: you can screen capture a QR code and re-use it later.
Right on the page, it says this.
Maybe I am not understanding your point. Both the website and the blockchain strategy make it impossible for you to record video content and claim it happened in the future, but neither of them defend against recording after the timestamp happened.
The blockchain strategy does not require a centralized service, while the QR code requires the website to be up forever.
There's also a way to generate the codes offline using a certificate chain and a fingerprint (https://github.com/qrdate/qrdate#static-qr-date-v1-spec) which does not require a website, just a key store. It needs more specifying to be viable for real world use but it should be possible. Help is very welcome.
AFAIK, signing off a timestamp and offering a public key to prove the timestamp was signed then doesn't seem to add value other than unnecessary complexity. I guess if there is a specific time you're trying to prove the event happened after, this system would offer higher fidelity than others, but not all.