350mb rips of prison break season 2 are around 624x352 pixels ripped form a progressive hd signal
the maximum pal resolution from a dvd is 720x576...that is for progressive...i doubt mnet would broadcast at that resolution
as tv is broadcast interlaced, you have to halve the horizontal resolution
so you get 720x288 at best possible quality, best case scenario, when watching live tv on mnet.
one last thing..the actual rips taken from usa broadcast tv are with ATSC high definition digital signals. so even if you rip the mnet signal on your pc it wouldnt compare to the downloaded rips, as the mnet signal would be from an analogue source and would thus contain enough noise to make it unwatchable on large tv's (by my standards), and even if you are watching it directly, you arent using dvi or hdmi to hook it up to your tv, so you still have an analogue path (which lessens the quality)
when it comes down to it, the 350mb download is a better quality than you get over the air (i record prison break series 2 on analogue tv tuner here in the UK and it doesnt compare to the hdtv rips)