Thanks for the update, that is definitely indicative of memory failure. I would next recommend finding the culprit stick by testing one stick at a time and testing in different slots to rule out a DIMM slot / mobo issue. Also, remember that Memtest can also shoot errors if you have your memory configured improperly / in the wrong slots. Just some other things to note :)
Also, in regards to your question, Memtest really never "ends", it just keeps going and going. It's essentially performing different tests and running through its algorithm to see if the memory cracks under stress.