Hi there, I will let an expert answer the vimeo question, but I can offer a perspective on the social media marketing part of your query. The short answer is: it depends! If you have a small budget (say under $2000/month) then you are probably best to manage yourself or inhouse, and upskill with training on latest tools or techniques. But as your spend level increases you probably want to be across more technical details and be managing multiple campaigns and audiences, reviewing ROIs, etc. So you might hit a stage where an expert enables you to spend more effectively and effectively. If you are going to work with a third party, be very clear about your brief and requirements and budget. Ask for recommendations and references, and once you find some one you want to work with, agree a joint plan, with milestones and review dates. That process makes it much more likely you will be aligned on expectations and get great outcomes.
Good luck, Vicky