If they came to hear me beg achievement

Am I missing something with this achievement? I have done the jumping and stoping my spring in mid air, assassinated the elite SO many times. I am just wondering if there is another way to get this other than The Pillar of Autumn beginning?
Can’t seem to get this to work for some reason, any tips?

Two videos of my many tries right here
http://www.bungie.net/stats/reach/fileshare.aspx