He studied animation at Kent Institute of Art & Design in England, and at Volda University College in Norway.

[3] Lasse originally submitted Hyperactive to YouTube after seeing a copy uploaded by another user with poor sound quality.

He has had several videos featured on the YouTube front page, including Hyperactive, What The Fuck?, Amateur, and Sogno ad Occhi Aperti.

While Hyperactive has been the most popular,[2] Amateur was featured in an article in the online edition of the Wall Street Journal.

[3][11] In 2007 Lasse worked on a two-part music video collaboration, named Sogno ad Occhi Aperti, with the Italian Cellist Giovanni Sollima.

[12] From 2019, Gjertsen has been working with VFX and voice on the children's show "Minibarna" for the Norwegian broadcaster NRK.