That spec iMac is the same that I am using, except I am using a 1TB Fusion Drive instead of just a SSD, although, there are inconsistencies in what you are posting:
it also has nvidia geforce gtx 675mx graphics with 1gb gddr5 memory. is that good?
This model utilises the GeForce GTX 680MX with 2GB of dedicated memory for graphics processing,
Which one is it?
My iMac has the 680MX with the 2GB VRAM, and it is the best GPU that you can get for the iMac for that year, but if the one you are getting has the 675MX, then that could change things.
My iMac is a beast. I thought that I would have replaced it by now, but there is no need at this point. I don't play WoW anymore, but when I did, I was able to play it with most of the graphic settings on max. I do play WoW classic, and I play that with all the graphic settings to the max.
While I do not do too much video editing anymore, when I did it seem to perform well. It encodes video pretty quickly too.
A side note, I am still on macOS 10.13 and probably will be parked here for a while, although it is capable of having the lasted OS, at least for now.
Another good thing about this model is that it is able to do Target Display Mode, which turns your iMac into an external display for other Macs. This is something that newer iMac cannot do.
Overall, I would highly recommend someone getting a high-end Late 2012 iMac if they are trying to save some money, but still want a decent Mac.
But.........
This seems a little high for it. I understand that people might look at that price and then say try to get something newer, but I don't know what the Mac market is like where you live, so maybe that price is decent.
Maybe look around before jumping on the deal you found, because it is a 7 year old Mac.
But, then again, I wouldn't sell mine for less than $1,000 based off of what it can still do for me. I doubt I would be able to find a buyer quickly, but I wouldn't let it go for any less.