after looking again, it appears the entire stand is sitting on a furniture four wheeled dolly. i dont doubt the casters can hold the weight, but the way the stand sets on that dolly may be an issue. could have very well just had the tank sitting on the dolly to move it and decided they wanted to take a picture of it with water and filled it up
ive put some insane ammount of weight on a dolly before, but never for prolonged use. those casters can definatly hold the weight, but not sure if they will hold up to the test of time.