In 2000, Berntsen moved to the Austrian club SW Bregenz, where his former teammate from Lillestrøm, Jan Ove Pedersen also were playing.
[4] Even though Lørenskog was not promoted, Berntsen was head coach of a second-tier team in 2007 since Kongsvinger hired him as Vegard Skogheim's successor on 6 November 2006.
Berntsen led Kongsvinger to a strong fourth place in 2007 Adeccoligaen, two points behind Bryne which played promotion play-off.
[5] On 3 August 2008 he was hired as head coach of his youth-club Strømmen,[6] and saved the club from relegation to Norwegian Third Division.
[14] The club reached its all-time high, participating in the 2018–19 UEFA Europa League group stage.