If the Price is Right/Walkthrough
When Niko meets up with Phil from his apartment in Tudor he'll tell Niko that they are going to Port Tudor. Grab a vehicle and head over there. On the way Phil explains the plan. Dimitri is going to hand over the H to the buyers while they collect the cash.
Arrive at the exchange point in Port Tudor. Go to the exchange building down the street and watch another cutscene as Dimitri openly betrays Niko over the phone. Follow Bell onto the building's roof and destroy the skylight with Phil.
Jump into the skylight and immediately gain cover. The warehouse is crawling with goons. Use the SMG and Sniper to pick off some goons, then carefully go down the stairs eliminating any goons in sight. Continue on and gain cover. Eliminate a couple more goons and go down the stairs to ground level.
Gain cover behind the truck on the right and kill the rest of the goons on the ground. An assault rifle would be helpful in this situation. Jump over the scaffolding in the middle of the warehouse and go up another set of stairs. Cover Phil as you get closer and closer to the cash room. Once the area seems quiet, run down to the money room. Cutscene. A goon escapes with the money.
Chase the goon outside and ignore the big truck. Turn left and there will be a pickup truck and a dirtbike. Pick a fast vehicle from these two and chase the goon's truck avoiding the falling logs.
Shoot the truck repeatedly. Cutscene. The goon dies. (Alternately, if you chase the truck long enough without losing it, the driver will eventually stop and get out and start shooting, making him an easy target to be either shot or simply run over.) Grab the truck (or pick up the money if the driver was shot) and drive Bell over to Tudor (you may need to lose a wanted level), where he will give you a large slice of money and a debriefing cutscene.