The only way you're going to be able to do this, unfortunately, is to buy a capture card for your computer and record the replay to your PC as it plays on the PS3. The reason is that when games record replays in this style, they don't record video data, they record the game data and recreate the match/race/whatever when you go to watch it.
I stream on twitch.tv and such so I have some experience with this stuff. If you really want to record gameplay footage enough to invest in it, I recommend the Elgato Game Capture HD or the new HD60. I use the regular HD and even with stream compression my footage ends up looking pretty good. If this was pre recorded footage rather than streamed it could be perfect 1080 without all that compression, but that's really a limitation of my internet rather than the device.
I stream on twitch.tv and such so I have some experience with this stuff. If you really want to record gameplay footage enough to invest in it, I recommend the Elgato Game Capture HD or the new HD60. I use the regular HD and even with stream compression my footage ends up looking pretty good. If this was pre recorded footage rather than streamed it could be perfect 1080 without all that compression, but that's really a limitation of my internet rather than the device.