Is it permissible to market natural products for weight loss and cosmetic products for treating the effects of accidents, surgeries, and sagging, and to work for a foreign company, given the presence of non-observant girls in the work environment and marketing videos?

The products mentioned are originally permissible, and there is no objection to your husband accepting work in marketing them. The fact that the company belongs to a non-Muslim country does not prevent working with it in what is Islamically permissible, and there is no assistance in harming Muslims. The presence of some objectionable content in the video clips does not make his work forbidden, but he must remove the objectionable content and forbid it to the best of his ability.