Listing inner-department seminars/presentations that focused on presenting current research by other authors?
I don't think it's improper per se, but I would not include them.

These sorts of presentations are more akin to assignments for a class: they can improve your skills in terms of public speaking and also getting deeper into the material.

However, you wouldn't put your course assignments on a CV, and I wouldn't put these presentations on a CV either.

I wouldn't even include them if they were based on original work, unless they are in a format that indicates some level of acceptance or prestige: conference presentations, invited talks at other institutions, etc. Instead, you reference that original work where it appears in public: in publications, for example.

They might be appropriate in a more generic form in a non-academic CV, when the point is to emphasize your experience presenting these sorts of things to a public audience, rather than your academic credentials.