Credit: Damian Gatkiewicz ESL
The act of run boosting involves you running on top of another running player, allowing you to jump farther than a regular jump would. When doing a run boost, this should be done on flat surfaces, but as you are getting more comfortable in your run boost, you can start doing it with the guns out and in different places.
If you take a closer look at the clip, you can see him and hampus decide to run boost Aleksib on the box mid-site, which gets him through the smoke. The aspect of surprise is the key factor here. The CT´s do not expect a T-player coming over the smoke and landing on the site. The moment Aleksib takes the first contract, hampus is going to swing to take the duels with the new IGL of NIP. By doing a run boost, the three players of NIP take down the B-site defenders of Lilmix.
Watch the clip right here: