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Probably not. It's illegal to rip Blu-Ray discs, so even if you find any .m2ts files on a torrent, your PS3 probably won't be able to play it. I know for a fact that Blu-Ray software such as PowerDVD Ultra will only read from a disc and not from a file on your HDD so I'm guessing the PS3 will be the same, seeing as Sony invented Blu-Ray.
You can rip onto standard DVD's (albeit a few of them for a full film!!) and it plays great on a PS3 - full high def....
720p is much smaller files tham 1080p and too be honest absolutely stunning in itself - so not sure you need to try and download full 1080p torrents....
A good programme is MKV2VOB which converts the "wrapper" into something you can burn onto a DVD and still retain the high def in all its glory - looks brilliant !