Club captain Cooper, winger Dallas and defender Berardi all watched the action unfold from the away end as they were joined by Bielsa's translator Salim Lamrani and United youth product Robbie Gotts for the 4-2 defeat.
Cooper, who picked up a knee injury against Sheffield United at the start of December which resulted in surgery, recently returned to full training and is expected to step up his comeback in the next week.
Dallas is also continuing his recovery from a foot fracture, while Berardi has been ruled out until February with a hamstring tendon rupture picked up in early November.
United's players joined in with the short-lived wild celebrations as Berardi rushed to join his team-mates from the stand following Gjanni Alioski's goal in the second half.
Leeds were backed by 2,000 or so travelling fans at Forest as they made their voices heard on an afternoon of frantic action.
Marcelo Bielsa's side though fell to a disappointing defeat on New Year's Day.
United went behind after an early mistake from Adam Forshaw allowed Jack Colback to open the scoring for the hosts as his back pass fell short of Bailey Peacock-Farrell leaving the midfielder to round the stopper and tap home.
The Whites afternoon was to get worse on the stroke of half-time as Kalvin Phillips was handed a straight red card following a heavy touch from the 23-year-old saw him lunge into a challenge with Adlene Guedioura with referee Darren England giving him his marching orders.
United fought back despite being down to ten men as Leeds turned the game on its head after the break.
Substitute Jack Clarke levelled just minutes after coming on before Gjanni Alioski sent the travelling fans wild, including Berardi who joined in the celebrations from the away end, before Forest mounted a comeback of their own.
Aitor Karanka's men though bagged three goals in seven minutes with Colback, Daryl Murphy and Ben Osborn all getting on the scoresheet to seal the points for the hosts.