I just did this in under 45min. Very important hint: don't rush with the headshot!! I didn't notice the timer reset to 4 sec in the end and killed the hostage like 4-5 times cause I thought I had less time >_<
I only used this video, it shows the best path and the places to throw flashbangs. For the rest you just need some luck (I often got killed because I got hit by the toilet guy's dying shots or because my team mates didn't take out the guy in the right in the first room). At the end I flashed and ran and shot 3-4 guys from up close, I died a lot there but most of the time they try to melee you and miss cause you keep running. When you know their positions just start shooting a little before you can see them or they might hit you first.
Personally I found the 9 minute mission in the nuke base on Veteran harder than this one.
Now to kill some tv's and steal some laptops...