I don't quite get what you mean then. How exactly is astroturfing refutable? If I am accusing you of astroturfing, how would you refute that accusation?

She says in the presentation:

As for your own doctor, the medical lecture he attended that had all those positive evaluations was in fact like many other continuing medical educations classes sponsored by the drug company.

This questions the validity of the information provided to them. Not their character.

I wrote scientists, but no, she definitely attacks the character of doctors. She basically says it just before the line you quoted: https://www.youtube.com/watch?v=-bYAQ-ZZtEU&t=397

As for her remarks about those who approved the drugs being paid by the drug companies, that could theoretically be considered an ad hom. However, financial incentive for a certain outcome in subjective matters (such as being a decision maker in an approval process) does indeed give good enough reason to raise eyebrows.

Would you be suspicious if a the panel of judges for Olympic figure skating got paid by China after their person won the gold? It doesn't automatically mean the person who won didn't deserve to. But the validity of their win is certainly in question.

Yes, I would be suspicious and the accusation that the judges are corrupt would still be an ad hominem because you are attacking the credibility of the judges to make independent judgements. As I said before, there is nothing automatically wrong with an ad hominem argument.

I never said she was wrong because she used an ad hominem. I defended my own use of an ad hominem by pointing out that she makes one herself.

The study you posted suggests that those who receive money from companies hold opinions that are favorable towards companies. This is terrible and shitty, but she argues the converse of this. She says that if someone holds an opinion that is favorable for a company then it must be because they are paid by the company.