The problems surrounding Ninja Gaiden II's glitchy Mission Mode DLC continued as word is spreading that watching Mission Mode replays will give you achievements.
All you need to do is go to the karma leaderboards and click in the right analogue stick to get the option to download a replay video. When watching it back, you'll unlock whatever achievements that person has from Ninja Gaiden II.
It seems to randomly work with some players and not others - Darkness C4WM's replay (currently ranked 35th in the world) is confirmed to give you 210 gamerpoints as of now. Kinkeshi, currently ranked 285, is confirmed for 235 gamerpoints.
It's believed that the way the glitch works is it awards you the achievements the player had at the time of recording the video. Any achievements he unlocks after the video was uploaded won't be awarded to you.
A weird glitch and an easy way to boost your gamerscore before Tecmo comes back to patch it up. Just don't tell anyone how you did it!