I've actually seen that video before and honestly it doesn't seem like it would work considering you're gonna be pumping a couple hundred gallons an hour and water takes so long to cool...I'm assuming you would just pump less water but still...and I don't know where he's buying supplies but a new mini fridge that size is closer to $200 but still less than a chiller granted... (sorry if any of this sounded mean or condescending it's not what I meant)
it's an idea that's really interesting to me I just don't understand, please tell me how it works for you! and your tank size and how many degrees it cooled your tank once you get it up and running and figured out, best of luck!