They had to pick a foreman first. Then read through the charge. They then probably tore up pieces of paper to use as a ballot to take a secret nonbinding vote to see how many were leaning each way. Then they went through the ballots and saw that no one wanted to convict. They then talked about it for a few minutes to make sure they were all in agreement. They then took a formal vote, marked "not guilty" on the verdict form, signed it and called the bailiff.
Even when there is nothing to discuss it takes a responsible jury several minutes to do their job.
If it was like the trial on which I was on the jury, they were cooling their heels for a half an hour while the clerk finished the paperwork and the prosecutor pushed one last plea deal before we could even start deliberating.