thanks for the video and explanation, but damn, I tried for about 1 hour and didn't even manage to get it right once, which means for me to pull it off during a run probably won't happen :(
If anyone does pull it off though, sub 1:10 should be pretty easy to get.
Also I pulled off that other trick afew times(well, almost, I died trying to land at the stairs) i'm wondering if it could save any time compared to doing the level the normal way