[sr2]

Even if this site was not a joke, I wouldn't trust an online password generator, especially if the pass is generated on the backend instead of the client. A quick Google for 'password generator' yields hundreds of these sites which are more than likely run by the same outfit and are possibly logging the passes into a database to make cracking various accounts easier.

There's a few PW generators which run on the client only and don't send any requests to third parties, and I use them sometimes. They are typically very JS heavy and use different seeds to generate sufficient entropy, like client fingerprint, mouse co-ordinates, timezone, etc

[kcanini]

The Mersenne Twister algorithm takes a random seed (which should be highly entropic) as input and then deterministically generates a series of outputs. It does not generate any entropy by itself, nor does it specify where your source of entropy should come from.

[svenfaw]

If I'm not mistaken, using a Mersenne Twister in a secure application is a really bad idea.