I’m stuck at that part, too. While this is annoying enough (I just hate infinite spawns), every time I die the game crashes… 
Basically yeah. There’s some rockets for your own launcher (NOT the TOW, that’s for the bit after killing the Osprey) lying around. Turn off the laser guide, wait for the Osprey to hover and offload troops, then blast it. If you’re out of rockets, use the tau cannon and charge your shots.
I haven’t changed my tactic for the first part since HL. Peep out of every Hole now and then, kill the nearby grunts or hurt them (shotgun, grenades, mp5 with grenade launcher should be the weapons of choice here), then go back into the sewers, pop out on another hole and so on. Once your behind the tank, it’s really easy, even on hard. Get the rocket launcher and shoot straight through the Hole in the Wall the Tank has blasted.
As for the second… I’m not that far, I’m only at the first manta Ray encounter, you know the building with tons of tripmines in. 
Hello,
I seem to be stuck in destroyed building right after you restock in the makeshift armoury that. I simply have no idea which way to continue 
Jump to the small stairs in front of you. Then jump over the wall to the left. There should be a hold in the ground. Fall down that.
This is from memory, so it might be wrong
Thanks!
I really did not notice that back room and I just assumed I need to go top.
Oh damn. I didn’t think of that. You can also go around and jump in from the green cabinet. It’s possible but really hard. Took me like 15 attempts
To kill the soldiers from a safe spot I use the alien hand and bounce of the wall
Wow…I passed this using “lowjump” only…didnt know you could highjump. It took a really long time to get passed that way.
It may just be my luck, but I found that if you fire the rocket somewhat to the right of the chopper and then point the laser to the chopper so they hit on the side, it made a difference to me.
I actually had no problems with the Apache, since I still had ammo for the Tau cannon; but I disliked how it crashes. It flies too fast and twitches too much, it just looks weird.
I had fun in this room. It looked as if there were multiple paths to take to get to the elevator instead of just the one. which is a nice detail.
Ninja Skills! (Just avoid all explosives. This part is annoying)
Fighting it with a pistol cant be very effective.
My apache fight bugged out or something. I shot at it with about 7-8 rockets, then it flew away just to come back with its left side against me while shooting towards the cliff path you come from. I had to shoot it with 3 additional full tau-charges to have it crash into the cliff.
there were numerous times in that video you could have avoided its fire
In Surface Tension… you know the one 
A mini walkthrough of this little area would be hugely appreciated. As much as I hate asking for help, I can’t figure out the way through for the life of me and after about an hour of constant dying I am at my wits’ end!
Many thanks!
Jump across the lasers and don’t use the doors just continue down the hall once you get to the main room go through the shelves and break the wooden box once that is done go left and get the the room on at the end of the passage go upstairs look down at a box on a lift and shoot it until it breaks then press the button and get on the lift then run and jump into the the main lift and fist the hivecannon and take the lift down and win!
Thanks for the reply…
I’m up to here:
The stairs are just along the corridor to the right. Is that laser supposed to be jumpable?