That Mac mini looks like a pretty neat machine.
The mini is a neat little machine...and if it does what you need, it is great. You can’t add a vid card to it (except USB, I haven’t tried them).
That said, my daughter has an older mini. She can create movies, dvds, etc. It isn’t the fastest/most powerful, but she does way more with the included Apple iLife software than she was doing with the Dell it replaced. The Dell was basically a surfing/email box, and it played some simple games. The mini cost a bit more than the Dell, but was way worth it.